- 1 Preface
- 2 Founding
- 3 Original Team
- 3.1 Early Missions
- 3.2 First Graduation
- 3.3 Brotherhood Disassembled
- 3.4 Anti-Mutant Hysteria
- 3.5 Non-Mutant Threats
- 3.6 Factor Three
- 3.7 The "Death" of Xavier
- 3.8 Growing Pains
- 3.9 Havok and Lorna
- 3.10 The Return of Professor X
- 3.11 The Hidden Years
- 3.12 The Secret Team
- 3.13 Secret Empire
- 3.14 Second Genesis
- 4 References
A number of the incidents recounted in the early adventures of the X-Men are cited to have occurred in specific decades relative to the era of publication. However, the Earth-616 universe operates on a Sliding Timescale these events could not have occurred in the times they appeared due to the fact that it would drastically age the character. As of this writing, it's generally accepted that the X-Men have existed for roughly 10 years. All historically specific references to the activities of the X-Men will be generalized in the main article, and any references to the Sliding Time Scale will be mentioned in the citation notes.
This article pertains to the original team of X-Men founded by Charles Xavier. This group should not be confused with the group of mutants founded by the mutant later known as Wolverine, who are some times referred to as the "First X-Men". It should also not be confused with its offshoots, such as Cyclops' "Uncanny" X-Men,  or the time displaced "All-New" X-Men.
The Man Behind the X-Men
The X-Men were a group of mutants formed by Professor Charles Xavier, a mutant himself. Gifted with the power of telepathy, Xavier saw the growing prejudice towards the growing mutant population and became determined to create a world of peaceful co-existence between humans and mutants.
Charles journey that led to the formation of the X-Men began over the course of 20 years as he traveled the world. Charles had developed a formal education and became a leading expert on mutations. By the time that Charles was 16 he had graduated with honors from Harvard University, he also began attending Columbia University and later went on to Oxford University in England, netting PhD's in Genetics, Biophysics, Psychology, Anthropology, and Psychiatry.
Following his education and a stint in the military, Xavier began to travel the world. While doing humanitarian work he met another fellow mutant named Magnus. Eventually they came to disagree on the role mutants had to play in the world, Magnus feeling they should be masters of the Earth. Magnus would eventually become the mutant terrorist known as Magneto and begin gathering mutants of his own. Charles soon opened Xavier's School for Gifted Youngsters to educate and train mutants to control their powers and protect the world from various threats, but mutant and non-mutant.
Xavier had now met a number of other mutants and had grown concerned, and began formulating his first ideas to gather mutants and train them in the use of their powers for the greater good. Charles tracked down Moira MacTaggert, a former lover and a specialist in mutants in her own right, securing her assistance in tracking down mutants for his cause. Later Xavier's travels brought him to Tibet where he discovered a mysterious walled off city. Upon further investigation he discovered that the city was enthralled by the alien invader known as Lucifer and led a rebellion against the would-be world conqueror. Although Xavier foiled Luficer's plans, a falling block fell on top of him crippling Xavier from the waist down. Taken to a hospital in India, Charles was told by doctors that he would never walk again. He was then nursed back to health and put through physiotherapy with a young American nurse named Amelia Voght. Three months later the couple moved into an apartment together in Bombay. There Xavier began working on schematics for a mutant detecting computer he called Cerebro. Charles and Amelia later returned with Xavier to the United States to start up Xavier's School for Gifted Youngsters. Charles and Moira later set up a training facility nearby as well.
Forming the X-Men
Back in the United States, Xavier was contacted by John and Elaine Grey whose daughter Jean developed telepathic and telekinetic powers. Jean was traumatized when she was in the mind of her best friend as she died after being fatally run over by a car. After pulling Jean out of her shell, Xavier attempted to help her control her telepathic abilities. Through these early tests both Charles and Jean made contact with another young mutant named Scott Summers another mutant he would soon contact. Xavier continued honing Jean's telekinetic abilities until she developed moderate control. Xavier became aware of two other mutants, Pietro and Wanda Maximoff, and offered them to the chance to return with him to America to hone their powers. Pietro refused on their behalf, but they were later recruited by Magnus -- now calling himself Magneto -- who was also gathering mutants to his cause. Learning of Magneto's intentions, Xavier and Amelia traveled to the long abandoned Auschwitz concentration camp to confront Magneto on the anniversary of his time there during World War II. There Xavier attempted a final plea to Magneto to work with him to bring about peaceful co-existence between humans and mutants. However by this time Magneto had given in fully to his hatred of the human race and refused to listen. Upon leaving, Magneto warned Xavier that when they next met, it would be as enemies.
At that time, Xavier decided to take a more active role of recruiting mutants to his side and reached out with whatever resources available to him. He reconnected with Fred Duncan at the FBI's division on mutant affairs after increase reports of anti-mutant hysteria. When reports of Scott Summers' powers flaring out of control, Xavier convinced Agent Duncan to allow him to find and train the boy and other mutants to his cause. Using his mental powers to track down Scott, Xavier was too late to stop him from being recruited by another mutant, a crook named Jack Winters. Winters attempted to exploit Scott in order to access a cyclotron that would transform his body into living diamond. Xavier tracked the two rogue mutants there and engaged Winters in telepathic battle. Xavier lost the first bout when he was seemingly buried alive allowing Jack to access the cyclotron and transform himself into pure diamond. Having survived, Xavier saved Scott from arriving security and convinced the boy to help him stop Winters. Now calling himself the Living Diamond, Winters attacked both Scott and Xavier. Unable to stop their foe on their own, Xavier guided Scott on how to operate the cyclotron bombarding Winters with too much energy causing him to implode. Taking Scott back to his school, Xavier made him the first of his new team -- the X-Men -- giving him the code name Cyclops. By this point Amelia had enough of Xavier recruiting mutants to his cause and begged him to walk away from it all to be with her. When he could not choose, she attempted to walk out on him and in a panic he tried to stop her with his mental powers. Horrified by what he had done, Xavier released his control from her, but the damage had already been done and Amelia Vought walked out of Charles life, seemingly forever.
Xavier later became aware of another mutant, the wealthy Warren Worthington III, who had feathered wings that enabled him to fly. Unable to get to Worthington right away, Xavier telepathically guided the youth when he was being attacked by a religious fanatic who believed his "angelic" mutation was an affront to god. The next mutant he actively sought out was young Robert Drake, who could control and manipulate ice. When Drake was arrested after freezing a bully in a block of ice, Xavier and Cyclops traveled to Fort Washington. Learning that Bobby was in jail and a lynch mob sought to hang him, Xavier sent Cyclops to rescue the boy. Bobby refused to go with Cyclops and the two eventually came to blows  until the mob caught up with them. Xavier soon intervened, using his mental powers to erase everyone's memories of Bobby's ice powers and invited him to join the school. Bobby agreed, and he became the second X-Man, codenamed Iceman. Meanwhile, Xavier began petitioning the Grey family to allow their daughter to join his school.
Xavier then began focusing on Warren Worthington once again, who had now began a solo career as a costumed hero calling himself the Avenging Angel. Tracking Angel down, Xavier sent both Cyclops and Iceman to recruit him just after the Avenging Angel succeeded in recovering a stolen vial of a radioactive isotope. However the isotope had an effect on the Angel's mind and he battled the two X-Men. With the isotope reaching critical mass, Xavier successfully contacted Warren telepathically and convinced him to toss the isotope high in the air where it harmlessly exploded. His sanity restored, Warren also agreed to join the X-Men, re-christening himself as simply the Angel. Soon Charles began reading about Duffee, Illinois high school football star Henry McCoy whose enhanced agility and large hands and feet identified himself as a mutant. However, Hank's abilities also attracted the attention of the terrorist known as the Conquistador who sought to utilize those powers for his goals of conquering the world. The Conquistador then captured Hank and his parents before Xavier and his other students could reach him. Charles managed to track Hank when he was forced to break into a nuclear research facility to steal a newly invented solar power device. Xavier sent his X-Men to rescue Hank and his family from the Conquistador's lair. In two accounts the rescue was a success and the Conquistador was seemingly slain in the ensuing blast when the solar power device overloaded. However another account states that there was no explosion and the Conquistador apparently did not perish. Like the others, Hank agreed to transfer to Xavier's school and join the X-Men taking the code name Beast. As with Iceman, Xavier then used his mental powers to erase all knowledge of Hank's mutant powers from the people in town.
With Jean Grey joining the group, Xavier's team of X-Men was complete. He began training them to hone their powers in his specially constructed Danger Room. Early on there was trouble when Hank began to get upset that Xavier used his powers to erase all memory from the people he grew up with. Hank soon became angry at this decision, but Xavier eventually convinced Hank that it was for the good of those he knew and loved, as well as his own personal safety. In training, Xavier taught Beast to never underestimate his adversaries. Discovering another mutant, Xavier and Moira attempted to convince the wealthy Winston Frost to enroll his daughter Emma into his school. When Winston would not consider it, Xavier telepathically contacted Emma and tried to convince her to join his cause. However she refused when Charles offered to alter her father's mind to change his mind and Xavier and MacTaggert left empty handed. Xavier and Moira then began comparing notes, including files on foreign mutants Ororo Munroe, Peter Rasputin and Kurt Wagner. Xavier began planning to try and recruit them into his X-Men once he had a more international reach. However this would not come to pass as he began focusing on the threat posed by Magneto to humanity at large.
Now calling himself Professor X, Xavier was ready to reveal the X-Men to the world. Soon the threat of Magneto became very real and Xavier called upon his X-Men to prepare for their first battle against his one-time friend. Through Xavier's guidance, the X-Men succeeded in stopping Magneto from taking over the Cape Citadel missile base, forcing the master of magnetism to flee. Due to his exemplary work in the field, Xavier selected Cyclops to act as the field leader for the team, despite Scott's fears that he was not worth due to the lack of control he had over his powers. Later when the mutant teleporter known as the Vanisher began stealing government secrets, Professor X offered the X-Men's aid to the government to stop him. Xavier himself defeated the Vanisher by using his mental powers to cut off his access to his powers, allowing the X-Men to easily capture him and his minions. Later when the Angel had another personality shift following exposure to radiation unleashed by a test by Stark Industries, X-Men stood back to allow the armored hero Iron Man deal with the danger posed by the Angel until he reverted back to normal. Xavier later agreed to return the favor when Iron Man sought the X-Men's aid in tracking down his rogue Avengers teammate the Hulk. However the Hulk ultimately evaded capture before the X-Men could get involved. The X-Men later met the supremely powerful hero known as the Sentry, assisting him in defeating his foe the General who was attempting to steal nuclear weapons to launch against the nation of France.
Xavier soon located another mutant, the immovable Blob who was working as part of a carnival freak show and sent the X-Men to recruit him. However Charles soon learned the error of welcoming the Blob in with open arms when he turned out to be uninterested in joining the X-Men and later attacked the school. While the X-Men kept the Blob and his army of carnies at bay, Xavier completed a device that allowed him to wipe out all memory of the X-Men's headquarters and secret identities from the mind of the Blob and his cohorts. Later while in a training session the X-Men were briefly surprised by the sudden appearance of a medieval knight, but it soon disappeared. After more training,  Magneto resurfaced, this time with his own team of mutants. This so-called Brotherhood of Evil Mutants conquered the South American nation of Santo Marco. Xavier soon deployed the X-Men who battled the Brotherhood, which also included Pietro and Wanda Maximoff who were now reluctant members of the Brotherhood as Quicksilver and the Scarlet Witch. When the Brotherhood was forced to flee, Xavier threw himself at a booby trapped door to save his students from the blast, and led them to believe that he had lost his mental powers as a result. Later when the X-Men were lured into a trap by Magneto and were taken aboard his Asteroid M headquarters, the X-Men managed to escape without the aid of Xavier. Charles later revealed to his students that he feigned his lost powers as a final test to see if his students could handle themselves without his aid. Soon Professor X was enthralled by the Puppet Master and the Mad Thinker who then used Xavier to order the X-Men to attack their foes the Fantastic Four. Although the two teams were forced to fight each other, Xavier eventually broke free from the Puppet Master's control and exposed the entire ruse. The Puppet Master and the Thinker then fled before they could be captured by the Fantastic Four and the X-Men.
The X-Men were later pulled forward in time by the hero known as Access where the Brotherhood of Evil Mutants had teamed up with the other-dimensional being known as Darkseid and his Apokoliptians who were attempting to conquer their two universes. The X-Men assisted the Avengers as well as the Justice League of America and the Teen Titans, heroes from Darkseid's dimension. Access used his powers to amalgamate heroes from both universes together and brought them to battle Magneto on Asteroid M. These included the Angel who was merged with the Teen Titan known as Robin , Bobby with the Titan's Impulse and Marvel Girl with the Justice League's Black Canary, creating the amalgams of Redwing, Quick Freeze, and Jean Black respectively. While on the Earth, Professor X, the Beast, and Cyclops remained to deal with the various threats there. When Access and his allies defeated Darkseid and Magneto, all the heroes and their foes were returned to their proper times and dimensions. Upon their return home, Charles and the X-Men's memory of events eventually faded. Learning that the Sub-Mariner was also a mutant, both Xavier and Magneto sought to recruit him to their respective sides. Magneto succeeded in summoning Namor first, ultimately leading to another battle between the X-Men and the Brotherhood of Evil Mutants. Realizing that Magneto intended to make Namor a subordinate he refused to join. The X-Men then drove Magneto and his Brotherhood away, but in the aftermath of the battle, Namor had no interest in joining the X-Men either. Charles next dispatched the X-Men to battle the Brotherhood again when they attempted to recruit Thor into their ranks, mistakenly believing him to be a mutant. When the X-Men arrived, Magneto and his minions then fled. Professor X and his students soon found themselves pulled forward in time once again. This time by a would-be assassin named Sidestep who was hired to assassinate the group of British super-heroes known as Excalibur, a future off-shoot of the X-Men, on behalf of the Latverian monarch Doctor Doom. To this end, each member of the X-Men had their memories altered to fit the era in which they were placed and forced to do battle with a member of Excalibur. Ultimately the more experienced members of Excalibur defeated the X-Men. With Doom's plot ruined the original X-Men were restored to normal, had their memories of these events erased, and were returned to their own time.
Once his X-Men had completed their high school educational and training requirements, Professor X threw a private graduation ceremony for them. After the festivities, Charles showed Cyclops the secret chamber where he had completed his first version of Cerebro. He then revealed that he was embarking on a secret mission and had selected Cyclops to run the school in his absence. Although Scott was reluctant to take the position, he agreed to do so. Without Xavier, the X-Men succeeded in stopping the Brotherhood of Evil Mutants from recruiting the Blob into their ranks. In Xavier's absence, the Beast was attacked by an anti-mutant mob and quit the team. However he came back when a new mutant threat calling himself Unus the Untouchable began terrorizing the city. Beast developed a device that boosted Unus' force fields so that he could not even touch food, and forced him to surrender. Scott later led the X-Men in an investigation of a supposed mutant calling himself the Menace and his Mutantmen army. With the aid of Spider-Man, the X-Men revealed that "Menace" was really a group of criminals exploiting anti-mutant hysteria to commit robberies, pinning the blame on mutants. Later the X-Men joined the Avengers, Fantastic Four, Daredevil, Doctor Strange, and Spider-Man in battling the super-powerful Sundown.Charles soon contacted his students and revealed that he was searching for the alien Lucifer, who was responsible for crippling him. Charles called for his X-Men to join him in Europe. Quickly captured, Charles learned that Lucifer had armed a bomb that could blow up all of Europe and that it was specially rigged to his heart, so that the bomb would go off if his heart was stopped. When the Avengers later arrived to investigate the scene. Charles had his X-Men hold the Avengers at bay until he was able to incapacitate Lucifer with a mental bolt. Charles then stopped the first between the two teams and explained the situation. Satisfied that the X-Men had the situation under control, the Avengers then departed. With the help of his students, Xavier disarmed the bomb. When Lucifer revived shortly thereafter, Xavier allowed him to go free as he had been thoroughly defeated.
With the next stage of their education and training, Xavier provided the X-Men with alternate costumes that they occasionally wore in the field. He also developed an addition to Cerebro which included an artificial intelligence that taught his students whenever he was absent or busy. When Xavier began detecting a strange force that was taking control of plants and animals near the mansion, he and the X-Men tracked the source near Greenland. There they prevented scientist who were studying global warming from drilling into the domain of ancient creatures that used to be the dominant species on Earth and were in the final cycle of their lifespan. This discovery convinced the scientist to drill elsewhere for their research. During a later training session, Jean attempted to get the other members of the team motivated by offering to go out on a date with whoever won a race to the Danger Room, a competition that was quickly quashed by both the Professor and Cyclops. Later the X-Men were invited to the engagement party of the Fantastic Four's Mister Fantastic and the Invisible Girl. Since Charles was keeping his ties to the X-Men a secret at the time, he and he students had to act as though they did not know each other. During a lull in activity, Charles allowed the X-Men to investigate reports of a savage man running loose in Antarctica. This led to the X-Men discovering the so-called Savage Land and finding an ally in it's ruler Ka-Zar during a clash with the primitive Maa-Gor and the native Swamp Men. Deciding to take a vacation, Charles took his students to the Florida Everglades and decided to pay a visit to his old colleague Curt Connors. Learning that Connors had once more transformed into the Lizard, he had Angel, Beast and Iceman assist him in capturing the Lizard and reverting him back to human form. Later when the rest of the team came down with the flu, Charles sent Cyclops on a lone mission to the Blue Ridge Mountains of West Virginia to investigate disappearances in the area. With Xavier's guidance, Cyclops rescued the missing people from a cave dwelling mutant known only as Frederick. As Frederick was mentally unstable, Cyclops was forced to seemingly slay him in order to save his victims.
Charles soon became aware of what appeared to be a new mutant and sent his X-Men to make first contact. This led to another battle with the Brotherhood of Evil Mutants. However, this new entity turned out be the cosmic being known as the Stranger who had come to Earth to study mutants. During the ensuing clash, the Stranger transformed Brotherhood member Mastermind into dense matter and captured Magneto and the Toad to examine, while the Scarlet Witch and Quicksilver decided their debt to Magneto had been paid and went their own way. Charles had Mastermind's inert body stored at the mansion until he could find a means of dealing with it. The X-Men did not have time to celebrate their victory as Charles' step-brother Cain Marko, who was transformed into the avatar of the demon Cyttorak attacked the mansion. Charles explained to his students how his brother was transformed by the Crimson Gem of Cyttorak into a human juggernaut during their military service while they prepared defenses for the mansion. Unable to attack the Juggernaut's mind thanks to a psi-proof helmet, Xavier contacted the Human Torch for assistance. While the X-Men kept the Juggernaut at bay, the Torch used his flame powers to remove Cain's helmet leaving him vulnerable to attack and eventually defeat at the hands of Xavier. After thanking the Torch, Xavier erased his memories of his encounter with the X-Men and the location of their headquarters. While the Juggernaut was defeated, the X-Men were seriously injured as a result and went through a period of healing. Meanwhile, Charles secretly contained the Juggernaut on the mansion grounds, keeping him in a state of coma. Eventually, the X-Men recovered from their injuries and Charles decided that they should all take a brief break from adventuring.
While the Professor was away, Scott and the others took time to relax, spending a lot of time at their regular hangout, Coffee A Go-Go, unaware that they were being observed by young Skrulls on a mission to infiltrate the Earth. When the Skrulls later posed as the X-Men to free various creatures that escaped from Monster Island, Cyclops and the others helped recapture the beasts. Realizing how selfless the X-Men were, the Skrulls later saved Scott and the others when their latest monster hunt went south, compromising their mission enough to get sent him leaving the X-Men confused about the entire ordeal. When Angel and the Scarlet Witch both appeared to have gone missing, Cyclops and the X-Men joined Quicksilver in searching for the pair. After a brief confrontation they learned that Warren and Wanda were briefly dating in secret until they realized that they came from very different walks of life and decided to amicably end their relationship. The X-Men soon were contacted by Charles who had gone missing while on a mission to Africa. Hearing his telepathic cry for help the X-Men hired the retired 1950s adventurer known as Gorilla Man to help them rescue Charles from a mysterious cave that sapped the wills of those trapped inside.
By this time, Marvel Girl had developed a friendship with the Scarlet Witch who was trying to reform herself after leaving the Brotherhood. When the Witch was secretly tapped by the spy agency SHIELD, Xavier was able to locate her and send his X-Men to help. In turn they learned that the Witch was assisting the Black Widow in stopping Hydra from stealing a new experimental sub. Charles used his mental powers to block Hydra brainwashing which led to the organizations defeat. The X-Men later assisted Thor in tracking down members of the Midgard Vanir who had kidnapped Iceman in a plot to revive the Frost Giant known as Ymir on Earth. By this time, Mastermind's consciousness expanded allowed him to use his illusion casting powers at great distances for a short period of time. Seeking to get revenge against the X-Men, he used his powers while the Professor was away to trick the X-Men into going on a "mission" to Monster Island. When Charles returned to the mansion and found his charges missing, he managed to tack them down and expose Mastermind's plot, defeating him in mental combat. Xavier then had Mastermind's inert body removed to a safer location where he could do no further harm. Cyclops and the X-Men later returned to the mansion where their training resumed as normal. Later bother Charles and the X-Men were later invited to the wedding of Mister Fantastic and the Invisible Girl, once again having to pretend to not know each other. The wedding was soon crashed by an army of super-villains under the control of Latverian monarch Doctor Doom a long time Fantastic Four foe. Cyclops led the X-Men against attacks made by the Mole Man and his Moloids,  Batroc the Leaper, the Executioner, and the monster Grogoom. Eventually Mister Fantastic dispelled the villains with a time displacement device provided to him by the Watcher and the wedding went on uninterrupted.
Anti-mutant hysteria had reached new highs at this point thanks, in part, to the bigoted fear mongering of inventor Bolivar Trask. Seeking to try and dispel some of the prejudice, Charles organized a televisted debate with Trask. Trask in turn used the debate to unveil his mutant hunting Sentinel robots to the public. However the machines soon turned on him, deciding that the only way to protect humanity was by ruling it. Charles summoned his X-Men, but they were too late to stop the Sentinels from absconding with Trask, although one of the robots suddenly deactivated in the battle. Before they could determine why, Charles led his X-Men out to the secret base of the Sentinels only to find it heavily fortified with powerful weapons. During the initial attack on the Sentinels fortress, both the Beast and Iceman were captured. While the other X-Men renewed their attack, Xavier probed the base and learned that the Sentinel's leader, Master Mold was probing the Beast's mind to learn what he could about the X-Men. Xavier prevented the probes from revealing anymore before his astral form was driven back by Master Mold, who detected his presence. With his X-Men still trapped inside, Charles decided to determine what stopped the Sentinel back at the TV station and used his mental powers to commandeer a ride back into the city. There he discovered that a giant crystal display at the Crystal Products Building was jamming the signal to the Sentinel, he made arrangements to have it flown to the Sentinels' headquarters. While Charles had the police and military jam the Sentinels, Bolivar -- having realized the errors of his ways -- sacrificed his life to seemingly destroy Master Mold. The X-Men also managed to escape, but were injured while the fled, particularly Iceman who was in critical condition.
Professor X accompanied the X-Men to the hospital in order to ensure that their secret identities were not exposed, although he was incredibly careful not to led the authorities or hospital staff suspect that he had ties with the group. When they X-Men became aware that Warren's parents were going to be making an impromptu visit to the school, Charles and his students tried to return home before their arrival. This led to everyone but the recovering Iceman to be captured by Magneto, who had escaped the Stranger's world. After releasing Xavier and his charges high into the atmosphere in a balloon, he captured Warren's parents. Charles used his mental powers to guide Iceman in stopping Magneto from using Warren's parents as genetic templates to create an army of mutant slaves. All the while, he also guided the X-Men in to getting back to ground while also contacting the Stranger to inform him of Magneto's escape. Sure enough, after the X-Men arrived, the Strange soon followed forcing Magneto to flee.
As it turned out the purpose of the Worthington's visit was to inform Angel that his Aunt Mimi had gone missing while exploring Brazil. Angel eventually tracked her down in the hidden domain known as the Land of Mists. It was here Warren decided to stay feeling that he belonged in this society that did not judge him for being different. When the other X-Men returned upset that Worthington chose to stay, Charles tried his best to console the team. By this time Charles the X-Men began working with FBI Agent Baker who seemed to occasionally replace Fred Duncan as liaison for the X-Men. He also got into contact with his colleague Able Stack and agreed to have Stack bring his robot X-50 to interact with his students. Xavier later dispatched the X-Men and X-50 to Mount Saint Helen's where there were sightings of Lava Men. Xavier later warned his students when it became known that the X-series robots were proving to be unstable. The Lava Men were eventually stopped, but X-50 was destroyed in the resulting battle. The X-Men recovered X-50's memory which Able Stack was later used to create X-51 later known as Machine Man.
The X-Men later crossed paths with the former Frightful Four member known as Medusa. Charles offered to assist her in recovering her lost memories but found doing so difficult. Suspecting that she was a mutant, Charles invited her to join the X-Men. When her former leader, the Wizard sought to bring Medusa back into the fold, the X-Men battled him. During the fight Charles realized that the Wizard had implanted a device on Medusa to control her mind. After Cyclops destroyed it, Medusa was freed from the Wizard's influence and went on her own. Charles then revealed a surprise to his students, revealing that Angel had returned to them. When Jean was struggling to find a role model in the male dominant group, Charles arranged for Marvel Girl to shadow the Invisible Girl of the Fantastic Four, assisting them in defeating the Mad Thinker and his Awesome Android with an assist from the male members of her team. Later, Xavier was not concerned when Iceman briefly left the team to work alongside the Human Torch. Bobby quickly returned to the X-Men when the Torch proved to be competition for the affections of Zelda Kurtzberg, the young barista whom young Drake was trying to woo at the time.
The group was soon attacked by Calvin Rankin who after an accident endowed him with the ability to mimic the abilities of those in close proximity to him, attacked the X-Men in the costumed identity of Mimic after learning their identities. During their initial clash, Mimic captured Jean and fled. The X-Men followed after Mimic when he kidnapped Jean and fled to the secret cave laboratory he lived. Here Mimic hoped to use the X-Men's stolen powers to open up a buried device invented by his father that Mimic assumed would make his power duplication abilities permanent. As it turned out this was not the case and Xavier allowed himself to be taken hostage while Mimic used the device which stripped him of his powers instead. Charles then erased Calvin's memories of his encounter with the X-Men and set him free. Lucifer resurfaced soon after, and he manipulated the Blob and Unus to team up and commit crimes dressed like the X-Men. The X-Men attempted to apprehend them and clear their names, but Blob and Unus managed to escape. When Xavier attempted to learn the identity of the Blob and Unus' benefactor he was incapacitated with with a mental defense weapon. After the Beast developed a device to block the effects of the mental distorter, Xavier led the X-Men after Lucifer. While Lucifer attempted to activate his Dominus computer to enslave the Earth, the X-Men attempted to infiltrate his fortress the Professor was captured by Lucifer's robots. Learning that only the robots could utilized the Dominus computer, Xavier instructed his students to destroy them, leaving Lucifer with no means of activating his computer. Unimpressed, Lucifer's superiors banished him to another dimension, ending his threat to Earth. Charles and the X-Men were later asked to assist the military in capturing the gamma spawned monster known as the Hulk who was sighted in the Pacific North West. However they soon learned from the Hulk's sidekick Rick Jones that the military sought to weaponize the Hulk. Feeling sympathetic for the Hulk's alter ego of Bruce Banner, Xavier and the X-Men let him go and acted as though their search was fruitless.
In order to better train the X-Men, Xavier designed the robot Colosso to hone their powers. After their training session Charles allowed his students to have a brief break from their studies and training. While the X-Men were gone, they were targeted by Maggia leader Count Nefaria who enlisted the aid of the Scarecrow, Planetman, the Eel, the Porcupine, and the Unicorn in order to capture the youths. When Nefaria offered the X-Men to join his organization they refused and were taken prisoner while he targeted Washington D.C. The Count then sealed Washington in an impenetrable dome and demanded a huge ransom to release it, framing he X-Men in the process. Upon learning this, Charles offered his "expertise" to the military in order to get close enough to Washington to send his Asteral form. Contacting his X-Men, Charles instructed them to play along. Having developed special leg braced to allow for limited mobility, Charles then infiltrated the dome when Nefaria lowered the shield to allow the X-Men to collect the ransom. While the super-villains fought over the money, Xavier infiltrated Nefaria's base of operations and deactivated his device. Tricking Nefaria and Unicorn into thinking they escaped with the ransom, Charles then mentally alerted the Coast Guard as they attempted to flee the country. In the aftermath of the battle. In the aftermath of the battle, Jean got a letter from her parents telling her that they enrolled her at Metro College. Although Jean was leaving Xavier's school, she still kept her ties with the team. Later, when the X-Men battled the insane entomologist known as the Locust, Xavier put on his leg braces again and disguised himself as a "wise old man" to try and get the Locust to see the errors of his way. When this failed, the X-Men foiled his plan to destroy America's wheat supply with giant insects. Back at the mansion, Charles began working to enhance Cerebro some more and got caught in a mental loop between himself and the computer. In order to save himself, Xavier pulled the sleeping X-Men into his mind where they worked to free him.
After assisting his students in rescuing children from a burning orphanage, Charles returned home to what was eventually determined to be a false reading of a new mutant in New York. The X-Men were deployed and encountered El Tigre, an explorer trying to find the second half of the amulet of Ahau god Kukulkan. Xavier attempted to assist them with his leg braces, but they malfunctioned, and the team had to leave Charles behind. The X-Men followed El Tigre and his minions to the American Museum of Anthropology but failed to stop him from recovering the second half of the amulet, endowing him with the powers of Kukulkan. Although El Tigre was able to now block Charles' mental probes, he managed to locate the lost city where their foe escaped to. The X-Men went there and eventually defeated El Tigre/Kukulkan, stripping him of his powers, however Cyclops accidentally injured Angel with his optic blast in the process.
By the time the X-Men returned from their mission, Charles became aware of a new mutant menace that threatened them and began actively seeking out new members to boost the X-Men's ranks. Charles contacted the Scarlet Witch and Quicksilver, but they turned down Charles' offer as they were with the Avengers. He also had the Beast and Iceman attempt to recruit Spider-Man, who also turned down their offer. At that same time, the Puppet Master resurfaced and attempted to take control of Xavier's mind, but Charles had already placed mental blocks to prevent this from happening again. When the X-Men found their new member, a newly restored Mimic, they were shocked when Xavier arbitrarily made Mimic deputy leader of the group. Soon after the Puppet Master possessed him instead. Charles then sent the X-Men out to defeat the Puppet Master, freeing Calvin from his control.
Charles then began training the X-Men and Mimic in order to prepare them for the coming battle. Their foes turned out to be a mysterious organization called Factor Three who sent their operatives Banshee and the Ogre to attack the school. As he was being forced to work with Factor Three thanks to a headdress rigged with a bomb, Banshee went out of his way to sabotage the Ogre's attack and ultimately the X-Men defeated the Ogre and freed Banshee from Factor Three's control. Later, the X-Men accidentally revived the Super-Adaptoid who had hidden itself on the Xavier estate. Seeking to turn the human race into androids like itself the Adaptoid attempted to start with the X-Men. Mimic made the ultimate sacrifice when he tricked the Super-Adaptoid try to duplicate the powers he mimicked off the X-Men. While the Adaptoid was rendered inert, Mimic was also made powerless and left the team. Soon after this, Charles, Jean and Angel were later captured by the mutant known as the Warlock who sought to make Jean his queen after a bid to take over the world. Charles channeled his mental powers to bring the rest of the X-Men to the Warlock's hideout. There the X-Men bested the Warlock's minions and while their foe was distracted, Xavier used his mental powers to force the Warlock back into a state of suspended animation.
With the threat of Factor Three still looming, Charles continued to train his students. He also attempted to bring Scott and Jean closer together. While returning some books to Jean at Metro College, Scott and Jean met scientist Ralph Roberts, the older brother of Jean's college friend Ted. When Ralph showed off his new cobalt powered armor, a combination of a previous blow to the head and the unstable technology caused Ralph to go on a rampage as the Cobalt Man. The rest of the X-Men were then summoned to help restore Ralph back to normal. Later, the X-Men threw a surprise birthday party for Jean. As a gift, Charles gave Jean a new green and yellow costume which she would end up wearing as a regular costume much later. Returning to his attempts to cure Cain, Charles strapped himself and his step-brother into a Energo-Transformer to try and probe his mind for a means of curing him. Instead the presence of the being known as the Outcast caused feed back that caused the machine to explode. While Charles was put in a coma, Cain was revived and endowed with Xavier's mental powers. The newly revived Juggernaut was too powerful for the X-Men and left after being mentally contacted and asked to join Factor Three. While Charles was in a coma, the X-Men were still able to probe his mind and learn of the origins of the Crimson Gem of Cyttorak and with the aid of Dr. Strange, Earth's Sorcerer Supreme. He sent Cyclops and Marvel Girl into the Crimson Cosmos where they battled Outcast and recovered a Crimson Gem and returned to the Earth dimension. There they tricked Juggernaut into taking it, banishing him to Crimson Cosmos before he could join Factor Three. However while the X-Men were busy defeating the Juggernaut, Factor Three kidnapped the Professor.
The X-Men began trying to search for Charles, but were sidetracked when Jean received a call from Ted Roberts asking for help. They soon learned that his brother Ralph was captured by the subterranean ruler Tyrannus who sought to use Ralph to build a robot to battle his rival the Mole Man. While below the surface of the Earth, Angel, Iceman, and Marvel Girl were enthralled by the Mole Man with the mist of forgetfulness and sent to battle Tyrannus. They were later rescued by Cyclops and Beast, and the battle was ended when they exposed both Tyrannus and Mole Man to the mists, making them forget who they were. The X-Men then rescued Ralph and returned him to the surface. Back at Xavier's School, the X-Men received a partial distress signal from Banshee warning them that Factor Three was sending a "spider" after them. This turned out to be a spider robot, but the machine was destroyed by Spider-Man who happened to be in the area. Detecting the robot's arrival, the X-Men tracked it down and found the wall-crawling hero. Mistaking Spider-Man as the menace that the Banshee warned them about, the X-Men attacked him. However they realized their error when cooler heads prevailed they realized their error and let Spider-Man go. In the aftermath of the battle, the X-Men were able to track the location of Banshee's signal to a mountain range in Europe. However there was just one problem: the X-Men had no money to get there. Travelling into New York City to try and find a means of earning the money to fly to Europe, the X-Men ended up in a battle with Mekano, a disgruntled youth who used a powerful exoskeleton to terrorize the city. After stopping Mekano from trashing a new library, they unmasked him revealing him to be Tom Reagle, son of wealthy philanthropist Andrew Regal. Tom, as it turned out, was acting out because he felt his father ignored him. In thanks for stopping his son, Andrew rewarded the X-Men with the money they needed to make their trip.
The X-Men were later attacked mid-flight and were forced to abandon their plane. They were soon attacked by more spider robots and taken prisoner in the secret headquarters of Factor Three with Charles and Banshee. The young mutants learned that the group consisted of their old foes Vanisher, Blob, Unus, and Mastermind as well shapeshifter known as the Changeling. Under the leadership of the so-called Mutant Master, Factor Three were plotting to set off a nuclear holocaust so that the human race would be exterminated and mutants could rule the world. The X-Men managed to break free and escape from Factor Three. They then split up into two groups to disarm the bombs Factor Three planted to trigger this war. While Marvel Girl, Angel and Beast went to Russia, Cyclops and Iceman tried to disarm the bomb in America. However, the respective armies of both countries put up opposition. Meanwhile, Charles began trying to convince the already suspicious Changeling of Mutant Masters ulterior motives. The X-Men ultimately foiled Factor Three's plot and Xavier -- with the aid of Banshee and Changeling -- revealed that the Mutant Master was really a member of the Siris race who was attempting to exterminate humans and mutants so the Earth could be colonized. With his mission a failure, Mutant Master committed suicide over capture and the members of Factor Three disbanded.
The "Death" of Xavier
After their return home, Xavier helped the X-Men defeat a mind controlled scientist who rebuilt a Sentinel, and although Charles sought to determine how he as manipulated he never learned the source. The X-Men's attentions were later turned to Cyclops who started seeing visions of a demon running loose. With the aid of Dr. Strange they learned that the demon followed Scott back from the Crimson Cosmos and returned it there. While going to their usual hang-out, Coffee A Go-Go in Greenwich Village, the X-Men discovered that regular beat poet Bernard the Poet was a latent mutant. With the help of the Professor, the X-Men shut down his reality altering powers before anyone could get harmed. Charles later guided the X-Men in tracking down a strange reading picked up by Cerebro, uncovering the android Dragon Man. The creature was taken by Jean, and accompanied the X-Men on various missions for a time before Charles convinced Jean to let the dragon find a new home on Monster Island. Soon after, Xavier decided that the X-Men had passed their latest round of training and awarded them with new costumes. Charles soon learned that the alien Z'nox were planning an invasion of Earth and began preparing a means to stop them. While in the early planning phase he was visited by the Changeling who revealed that he was dying of cancer and wanted to make up for past wrongs. This worked perfectly to Xavier's plans. Confiding in Jean only, Charles transferred his mental powers to the Changeling who them posed as Xavier, and unlocked Jean's own telepathic potential. Charles then hid himself within the mansion in a heavily psi-shielded room to continue his work uninterrupted.
The other X-Men became aware that "Charles" was acting strangely, but never learned the truth. Posing as the Professor, the Changeling sent the X-Men on a mission to investigate reports of the discovery of the Frankenstein's Monster, to determine if there was a mutant connection. The X-Men battled what they thought was the monster, but soon destroyed it, exposing it as a robot. Using his borrowed powers of telepathy, the Changeling was able to learn that the robot was sent to Earth over 150 years prior to act as an ambassador for an alien race, but it soon malfunctioned. Soon the surface world was threatened by yet another subterranean dweller, Grotesk, who sought revenge for nuclear tests that killed his people and mutated him. When Grotesk threatened to use a device to destroy the surface world, the X-Men fought back against him. During the final battle against Grotesk, the Changeling sacrificed his life to destroy the creature's machine, seemingly slaying Grotesk as well. When the Changeling died, he remained in Xavier's form leaving the X-Men to believe that Charles was dead.
A funeral was quickly arranged for the man whom the X-Men believed to be their mentor, but the mourning was disturbed by the arrival of Quicksilver who had come to pay his respects. Later they watched what they thought was video confession of the Professor telling them that he had a terminal illness and before his passing endowed Marvel Girl with telepathic powers. The "Professor" also warned that Magneto had returned and soon the X-Men were out hunting their old foe. Tracking down his new hideout, the X-Men were unprepared to fight Magneto and his reformed Brotherhood of Evil Mutants and they were quickly captured. Although the team was shackled, Marvel Girl was able to free Angel and he fled Magneto's base to seek out the Avengers and get their help. While the Angel managed to make it to the Avengers, Cyclops also broke free and battled Quicksilver when suddenly the Avengers arrived. Magneto had prepared for this and planted a bug on Angel for the Avengers to find, making it seem like he betrayed the Avengers. He then used a mind control device to turn the X-Men into his slaves and ordered them to attack the Avengers. However the Avengers found the bug, and realizing Magneto was leading them into a trap only pretended to incapacitate the Angel. Free once more, the Angel freed the X-Men, and the Brotherhood was forced to flee setting their base to explode. The X-Men, Avengers and most of the Brotherhood escaped, and Magneto was seemingly killed in the blast.
Back at home, the X-Men continued to mourn the apparent loss of their leader. They had Xavier's will read to them by attorney Foggy Nelson who informed them that Xavier's school and financial assets were being given to his students. The X-Men's mourning was interrupted once again, this time by the Juggernaut who was brought back from the Crimson Cosmos by one of the Professor's machines. The X-Men battled the Juggernaut who could not believe that his step-brother was dead and when he saw the tomb stone for himself thought it was a trick. However the Juggernaut's return to Earth proved only temporary and he was shunted back to the Crimson Cosmos. In the aftermath of the battle, FBI agent Fred Duncan told the X-Men that in order to handle mutant menaces, the X-Men had to be broken up across the country. Before leaving, Iceman and Beast went on one last date with their girlfriends Zelda Kurtzberg and Vera Cantor. This led to another clash with the Warlock who was posing as a stage hypnotist calling himself the Maha Yogi.
Soon Bobby and Hank were sent out to the west coast, while Scott and Jean were ordered to remain in the New York area, while Warren was assigned to travel all points in-between for mutant menaces. Cyclops and Marvel Girl later stopped the android known as Quasimodo from stealing devices needed to enhance his Computo and its army of Cybertron robots. The government mandate that the X-Men remain apart proved to be short lived when the mutant known as Mesmero used his powers to awaken latent mutants across America and gather them in his Mutant City on the west coast. One of these mutants was a young girl named Lorna Dane who was saved from traffic by Bobby, who instantly became smitten by the girl. While the X-Men began trying to track down Mesmero and his mutant army, Iceman and Lorna were captured. The X-Men managed to track down Bobby and Lorna and were shocked when Mesmero announced that Lorna was the daughter of Magneto, and that their old foe had seemingly survived their previous encounter. The X-Men were no match for Mesmero and Magneto, and worse Lorna was conflicted as to where her loyalties were. The X-Men were then forced to flee, and come up with a new plan. Cyclops then developed the identity of Eric the Red, and sought to infiltrate the Mutant City from the inside.
While Cyclops succeeded in infiltrating the group, the X-Men's cover was blown by Iceman who disobeyed orders to stay behind because he was too personally invested in the fate of Lorna Dane. In the ensuing battle, Bobby convinced Lorna to renounce her alliance to Magneto after revealing documents that proved that he was not her father. The X-Men then destroyed the Mutant City, fleeing from their captors. Back in New York, the X-Men were invited to attend the wedding of the Avengers Yellow Jacket and the Wasp. Testing out some of Xavier's abandoned machines, Marvel Girl later accidentally pulled the Negative Zone tyrant known as Blastaar to their dimension. The X-Men proved no match for Blastarr, but eventually the very energies that brought him to Earth, seemingly slew him.
The X-Men soon learned that Cyclops had a younger brother, Alex, and they paid him a visit to Alex when he graduated from university. However, the reunion was marred when Alex was kidnapped by the so-called Living Pharaoh. The Pharaoh managed to kidnap Alex while framing Scott for murder at the same time by faking his own death. Cyclops was later captured as well and brought to Egypt with his brother. There he learned that his brother was a mutant as well, able to control cosmic energy, but his powers were tied to the Pharaoh. The Pharaoh had kidnapped Alex and planned to used a device to boost his own power. When the X-Men finally tracked them down to Egypt a battle broke out and ultimately the tide of battle was reversed when Alex manifested his mutant powers for the first time. Alex was horrified by the level of power he commanded and while the X-Men tried to calm him down, they were attacked by the Pharaoh and his minions again. Alex was captured again and placed in a device to channel his powers into the Pharaoh transforming him into the gigantic super-powerful Living Monolith. However the Monolith was easily defeated when Alex managed to overload the device causing a massive explosion. The destruction of the machines caused the Pharaoh to revert back to human form, but Alex was still terrified of his powers.
Havok and Lorna
While the X-Men had to deal with the Egyptian authorities, Alex fled into the desert. Unaware of this, after the X-Men escaped the authorities, they learned that Lorna Dane had been kidnapped from her home. While Bobby and Hank returned to the States to search for her, while Cyclops, Marvel Girl and Angel remained in Egypt to look for Alex. From Lorna's trashed apartment, Hank and Bobby soon learned that Larry Trask -- son of Bolivar -- and federal judge Robert Chalmers had reactivated the Sentinels and actively sent them out to capture mutants. Unknown to the X-Men at the time, this is what happened to both Alex and Lorna. Iceman and Beast were then attacked by Sentinels, while Bobby was captured Hank managed to escape and warned the others who rushed back to the United States. At Larry Trask's Sentinel base Bobby was reunited with Alex -- equipped with a uniform that controlled his powers and given the code-name Havok -- and Lorna. Soon Larry's Sentinels kidnapped Angel, Mesmero, and other mutants. Soon Cyclops, Beast and Marvel Girl located Larry's base and began to infiltrate it. Realizing that Larry intended to execute all mutants without a fair trail, Judge Chalmers removed a necklace from around Larry's neck that nullified his own mutant powers. However this was too late as his last orders to the Sentinels were to destroy all mutants. The remaining X-Men battled the Sentinels, tricking them by switching costumes with the recently captured Quicksilver, Scarlet Witch and Toad. Ultimately, Cyclops tricked the Sentinels into defeating themselves by convincing them to attack the source of mutations, radiation, and nearly the entire Sentinel fleet flew into the sun. However during the course of the battle, Havok was seriously injured.
With Larry Trask's plot in shambles, the X-Men fled, and Scott sought out one of the Professor's old colleagues, Karl Lykos to treat Alex's injuries. What the X-Men were unaware of was that Lykos was a non-mutant variant who required the life forces of others to live. Absorbing some of Alex's life force caused Lykos to transform into the pterodactyl-man Sauron who then went on a rampage across the city. Although Scott ordered the X-Men to lay low amid growing anti-mutant hysteria, Angel decided to go into action against Sauron. The X-Men went after Sauron and battled him, but as the creature's powers began to run low and a reversion back to human form began, Sauron hypnotically controlled Angel and had him bring Lykos back to his lab. The X-Men later recovered Alex, but soon the connection between Lykos and Sauron was revealed when he absorbed life energy from Lorna Dane and transformed into Sauron again. Ultimately, Sauron fled to the origin of his transformation into a non-mutant variant, Tierra del Fuego. The X-Men confronted him there with Lykos' fiancee Tanya Anderssen. But Lykos seemingly committed suicide by jumping off a cliff. Angel went after Lykos first and was knocked out ending up in the Savage Land. He was rescued by a man calling himself the Creator and his Mutates. Who claimed that they were being persecuted by Ka-Zar and his people. The other X-Men found their way into the Savage Land and met with Ka-Zar, learning that the Creator and his Mutates were actually the ones terrorizing the region. Meanwhile, the Creator gave Angel a new costume and convinced him to fight against his own teammates. None suspected that the Creator was actually the X-Men's old foe Magneto.
During the ensuing battle between the X-Men and the Mutates, Magneto revealed his hand unleashing his latest creation Loreli who could enthrall men with her voice. This had no effect on Marvel Girl who used her telekinetic powers to unleash Cyclops' optic blast, destroying Magneto's machines that sustained the Mutate's powers. As Magneto's citadel exploded, the X-Men fled, and their long time foe seemingly perished once again. On their way back to the United States the X-Men stopped in Washington D.C. where they clashed with the Japanese mutant named Sunfire who was attacking the capital to avenge the nuclear bomb drops on Hiroshima and Nagasaki during World War II. Sunfire was being encouraged to make these attacks by his uncle Tomo Yoshida. But it was not until Sunfire's father Japanese delegate Saburo Yoshida was killed by his uncle Tomo did Sunfire realize the errors of his ways and surrendered to the authorities.
The Return of Professor X
By this time Xavier was finally ready to fend off the Z'Nox invasion. He revealed himself to Havok and Lorna, who had been waiting at the mansion while the X-Men were away, but they soon returned. Briefing them on his deception and the impending invasion, Charles quickly resumed leadership of the X-Men and began preparing them for the final battle. As the X-Men battled the Z'Nox invaders, Charles linked his mind with every good human being on the planet and channeled these alien emotions to the Z'Nox via his X-Men, forcing them to flee. The strain caused Xavier to suddenly collapse. Unknown to Charles at the time, this effort also put him in psychic rapport with Shi'ar Princess Lilandra Neramani, a connection that would have far reaching consequences in his near future. In a coma and in ill health, Charles mind was probed for a possible solution to his condition. Xavier told them to seek out Bruce Banner and recover a gamma powered device that could cure him. The X-Men succeeded in recovering the device and curing Charles, but not until after a clash with Banner's alter-ego the Hulk and the military. Although the X-Men were reunited once again, and had the addition of Havok and Lorna Dane in their ranks, already the group was beginning to fray once again as a growing love triangle bloomed between Lorna Dane, Havok and Iceman. Lorna was quickly becoming more interested in Havok, making Iceman instantly jealous and possessive.
Shortly thereafter Spider-Man's foe Kraven the Hunter publicly "outed" Spider-Man as a mutant. Although still in recovery, Charles was at least able to help his X-Men to pinpoint Spider-Man's general location. The original team went to search for Spider-Man tracking him down to the Coffee Bean in New York. This location was attacked by Kraven and the Blob forcing the X-Men and Spider-Man to reveal themselves. While Kraven and the Blob were defeated by the heroes, Kraven completed his actual goal: collecting DNA from the X-Men for his employer, the enigmatic geneticist known as Mister Sinister, a man who had be secretly invested in the lives of the X-Men for years. When the Fantastic Four were later threatened by a mysterious foe, their leader Mister Fantastic contacted Charles Xavier for help protecting his family. Charles invited the Fantastic Four to his home and offered two deactivated Sentinels to help defend the Fantastic Four's headquarters. Unfortunately, the FF's mystery foe -- secretly their longtime enemy Dr. Doom -- had hacked into the Sentinels and sent them on a rampage through New York City. The Sentinels were stopped thanks to the combined efforts of the X-Men, Fantastic Four, Spider-Man, Daredevil, and Dr. Strange. Meanwhile, Charles and Marvel Girl stopped a Doom controlled Colosso from stealing Cerebro back at the mansion. The X-Men later wished the Fantastic Four luck on defeating their mysterious foe. Later when Doom absorbed the power of Galactus,  the X-Men were one of the many heroes who tried to defend the Earth from Doom. Charles and the X-Men were later seemingly slain. Ultimately Mister Fantastic defeated Doom with the Cosmic Cube and used its power to undo the damage cause, restoring all the slain heroes to life.
Finally back in full health, Charles had the X-Men brief him on their activities while he was in hiding. But the treatment appeared to have an effect on Xavier's mind as he began treating his X-Men like they were still students. First they showed him the Sentinel ships that they had captured in his absence. Charles used this opportunity to test their abilities by creating a mental battle between the X-Men and illusions of their greatest foes. The subsequent test was poorly received by Iceman, who was upset at Xavier's deception as well as Lorna becoming more interested in Havok than him. Learning that his students failed to confirm if Magneto had died in their last encounter, Charles sent them back to the Savage Land to investigate. The original team, except Iceman who quit the team, went on the mission leaving Lorna and Havok in reserve. The group hit turbulence entering the Savage Land and were forced to crash land. They were soon knocked out by drug tipped darts from a local tribe. Detecting this, Charles ordered Havok, Loran, and Iceman to rescue them, Alex and Lora agreed but Bobby once again refused to follow orders. Meanwhile, the male members of the X-Men awoke to learn that Marvel Girl was sent to the land of the dead, and assumed that she had died in the crash. However, they soon learned that the natives were literal and that Jean was sent to an actual land. Cyclops, and Hank fought their way to the underground river where those who were dead or dying were sent to this land while Angel tried to locate it from the air. While Hank and Scott located an ancient and advanced city while Angel was knocked out by the strong wind currents. Havok and Lorna arrived in the Savage Land and began searching for their comrades, gaining the aid form Ka-Zar. Angel meanwhile was rescued by a flying woman named Avia and slaves who worked for the Nhu’Ghari who enslaved those sent to their "land of the dead" to build their cities. Back in the states, Bobby decided to finally answer the Professor's calls for help and search for his friend. Meanwhile, Scott and Hank evaded capture from the Nhu'Ghari while Marvel Girl awoke to find that the Nhu'Ghari served the apparent ghost of Magneto.
Magneto revealed to Jean how he survived their last encounter and used his astral form to trick the Nhu'Ghari to do his bidding by making them think he was a ghost. He then began collecting the restorative volcanic gas found in the region as part of a plot to enslave humanity and had a number of balloons filled with it ready to be launched. Cyclops, Marvel Girl, Beast and Angel were soon reunited and they battled Magneto, however the fight caused volcanic instability. Although they managed to flee the slaves, the X-Men found themselves trapped. Taking Magneto and Avia with them they attempted fled the destruction in Magneto's blimp, but soon found themselves caught in a massive storm. As they bucked the storm, Magneto jumped ship with Avia following after him. Angel tried to follow her but the storm was too powerful. With the blimp breaking up, each of the X-Men latched themselves to a different balloon in the hopes that they could ride the storm out and safely return to the surface. Cyclops, Beast and Marvel Girl found themselves crash landing in Africa where they were found by the young weather controlling mutant named Ororo Munroe. Meanwhile, Havok, and Lorna continued to search for the missing X-Men in the Savage Land unaware of their fates. Bobby's own search went south when the same storm that battered his teammate caused him to get washed ashore in the Savage Land with amnesia only to be found by Karl Lykos, who had survived their previous encounter. The X-Men in Africa soon learned that the massive storm was being gathered by an albino mutant named Deluge who sought to get revenge against the world for the life of prejudice he had to endure. Meanwhile, Angel and Avia were pulled out of the ocean by some fishermen who intended to profit from their discovery.X-Men: The Hidden Years #6 The X-Men in Africa managed to defeat Deluge, but had to overload his powers, seemingly slaying him in the process. As Havok and Lorna finally learned that their teammates had apparently left the Savage Land, Cyclops and the others returned to the mansion to find the Fantastic Four waiting for them.
The FF had come to Xavier to learn why he tapped their minds during the Z'Nox invasion and when the Fantastic Four's, Mister Fantastic, pointed out that the Z'Nox were still a threat the X-Men joined them on a mission into space to stop the alien invaders. During the battle Jean was briefly contacted by the Phoenix Force, and although her memories of the encounter were erased, this meeting would have greater repercussions for the X-Men much later. Ultimately, the Fantastic Four and the X-Men incapacitated the Z'Nox to ensure they would be a threat to no other race in the universe and returned to Earth. Back home, Charles took Hank with him to Iowa to make contact with a new mutant, a young girl named Ashley Martin who could control inanimate objects. The other X-Men were soon greeted by Warren's girlfriend Candy Southern who had important news for Angel, and so they began searching for him. Their search led them to a derelict ship out in the middle of the ocean. They learned that Angel was the prisoner of a mutant named Stefan Krueger who had in turn sold Warren to the Brotherhood of Evil Mutants, now led by the Blob. Seeking more money for himself and his army the Freaks, Krueger knocked out Scott, Jean and Candy to turn them over to the Brotherhood.
While Cyclops, Angel, Marvel Girl and Candy fought against the Brotherhood to free themselves, Hank and the Professor learned that Ashley was just a young girl with little control over her powers. In the Savage Land, Havok and Lorna found Iceman whose memories had been restored thanks to a battle between Magneto and Sauron. When Sauron defeated Magneto, he sought to live free from interference of the X-Men and used his hypnotic powers to send Iceman, Havok and Lorna away with no memories of their encounter.X-Men: The Hidden Years #12 In Iowa, Xavier was forced to use his mental powers to turn off Ashley's powers. As Cyclops, Angel, and Marvel Girl continued to fight the Brotherhood, the battle was complicated further by the arrival of Krueger, who realized that Mastermind ripped him off with illusionary money as payment for turning over the X-Men. Meanwhile, Iceman, Havok and Lorna returned to the mansion to find that Cerebro had detected another apparent mutant located in the Himalayan mountains. The X-Men ultimately defeated the Brotherhood and Krueger, turning them over to the authorities and recovering Avia. Back at the mansion, the X-Men were reunited with Beast who was sent back by Xavier. Also rejoining them was Iceman, Havok and Angel. Angel learned that Candy sought him out because his uncle Bert -- secretly the villain known as Dazzler -- was attempting to marry his mom. Reunited with Hank, who was sent back to the mansion by Charles, the X-Men rushed to the Worthington estate to try and halt the wedding. While the original team members went to stop the wedding, Havok and Lorna decided to prove they were just as useful as their more experienced team mates and decided to look into the signal in the Himalayas. Meanwhile, the X-Men managed to stop Burt from marrying Warren's mother, however he had been secretly poisoning her and she soon died as a result.
Cyclops, Marvel Girl, Iceman and Beast returned to the mansion while Warren stayed behind to see to his mother's funeral arrangements. Learning that Havok and Lorna went out seeking the signal picked up by Cerebro Cyclops and the others went after them. In the mountains they saved Havok and Lorna from the Inhuman known as the Yeti. The Yeti was stopped by the Inhuman royal and the X-Men learned that Lorna was captured due to her resemblance to Yeti's long deceased Skrull lover. When the X-Men returned to the mansion they soon found it had been infiltrated by Kraven the Hunter. Kraven sought to challenge the Beast to combat, a fight the Beast ultimately won. It was also around this time that a group of mutants calling themselves the Promise came out of a decade of cryogenic suspension and began seeking new mutants to join their cause. Their leader Tobias Messenger sought to recruit Lorna Dane as he found that the other X-Men were too indoctrinated in the philosophy of Charles Xavier to ever join his cause. As the X-Men were occupied with Kraven the Hunter, the Promise enthralled Lorna and called her to their secret headquarters. The X-Men went after Lorna, but were easily incapacitated thanks to the various mental powers of the Promise. Unable to convince the other X-Men to join them, Tobias forced Lorna and Havok to be put in cryogenic suspension with them. As a last minute decision he also allowed Lucy Robinson's request to place the Angel into suspension as well.
Tobias then placed the X-Men deep below the Earth in secret tunnels built by the Deviants centuries ago. Battling their way through the tunnels, the X-Men found themselves in Subterranea again and were captured by the Mole Man, who sought revenge against the mutants for his last defeat at their hands. Meanwhile, Lucy had rigged the cryo-pods that contained her and the Angel to release them after the others were put in suspended animation. Lucy then revealed to the Angel that she wished to leave the Promise and be reunited with the family she left many decades ago. While Cyclops and the other fought the Mole Man and his minions, Angel brought Lucy to her home to find that her family had no interest in a reunion after she abandoned them years earlier. Meanwhile, Magneto had formed an alliance with the Sub-Mariner to invade the surface world. Having completed most of his work with Ashley Martin, Xavier began trying to assist the Fantastic Four in fighting off the invasion. Charles contacted Angel and aided him in freeing both Havok and Lorna from cryogenic suspension. with Havok revived first, Charles sent him out to help the authorities with the Atlantean invasion, only for Havok to get attacked by a mob. Angel was sent to find the X-Men, who were still battling the Mole Man. While Warren managed to find the X-Men and helped them defeat the Mole Man, Xavier ultimately stopped Magneto and Namor's invasion by assisting the Fantastic Four. In the aftermath of this crisis, the Promise were freed from their cryogenic stasis and Avia was returned to the Savage Land. The X-Men later celebrated Hank's 20th birthday.
The Secret Team
Following their trials and tribulations the X-Men went on another vacation. Shortly thereafter, after another conflict with Iceman, Havok and Lorna seemingly left the X-Men. However they were later kidnapped by the Secret Empire, who was secretly kidnapping mutants for their latest attempt to conquer the world.Captain America #174 Charles was later asked by NASA to mentally probe a passing comet. In doing so, it caused a chunk of alien matter to detach itself and land near the mansion. When the X-Men returned home, the alien matter stripped them of their powers just as their home was attacked by an army of Sentinels. Although powerless, the X-Men used their combat training to defend themselves and keep the Professor safe. Realizing the X-Men no longer had mutant powers, the Sentinels ended their attack and instead targeted Quicksilver and the Scarlet Witch. The X-Men came to their rescue, and they soon found their powers were not only returning but becoming more enhanced at a rapid rate. Charles soon detected the alien matter thanks to his increasing mental talents, and realizing that this increase in power could be dangerous had his X-Men eject the alien matter ejected into space, causing the team to revert to normal. However the alien matter had an impact on the Nexus of All Realities located in a Florida swamp causing a disruption in time in space. Charles sent his X-Men to investigate and they were sucked into various portals to possible future realities. Channeling his mental powers through the Man-Thing -- the guardian of the Nexus -- Charles helped rescue his students and close off the rift. The X-Men were later called into New York by the Continuiteens who detected a disruption in reality. The X-Men uncovered that it was the work of Spider-Man's foe Mysterio who had stolen swamp water from the Nexus zone to alter reality.
Also around this time, Moira MacTaggart was locating and recruiting new mutants to be trained at her mutant research center on Muir Island. These mutants included the geo-morph known as Petra, the chronokinetic Sway, the evolutionary powered Darwin, and the energy absorber known as Kid Vulcan. Charles took a particular interest in Vulcan due to his lost memories and his ability to manipulate energy. He introduced Vulcan to the X-Men and had him train under Cyclops, noting that he had control over Cyclops' powers. Charles soon desired to make Kid Vulcan a member of his X-Men. Charles also attempted to recruit Emma Frost into his group again. Learning that she was now a stripper for the hedonistic Hellfire Club, Charles and Moira attempted to recruit her into their cause but found her reluctant to join them. When Charles revealed that the members of the Club were aware that she was a mutant telepath exploiting her powers, she was almost convinced to join them. When one of the Hellfire Club bouncers tried to get Emma to come back to work Kid Vulcan attacked. Realizing they made a mistake, Charles erased Emma and the bouncers memories of this encounter and aborted this recruitment attempt. Later, Charles had Beast lead the X-Men on a series of investigations of alien sightings on the behalf of the mysterious Agent Baker, who ceased being an FBI liaison with the team shortly thereafter.
With the rest of his team reaching the final stretch of their college education, Charles was secretly away on Muir Island, the X-Men began being attacked by a series of threats including rampant Danger Room robots, a returned Frederick,  and strange phantoms of the Juggernaut and an apparent "magnetic ghost" of Magneto  Charles returned to find his school in shambles. He called the X-Men back and learned of the recent attacks on the school. After advising his team that he intended to expand the scope of his school to an international level and focus primarily in training new mutants to control their powers and defend themselves, Charles and the others soon realized that the strange phantom attacks were coming from Jean's mind. Charles and his students then ventured into Jean's mind and helped her cope with her fears. With the crisis averted, the X-Men were soon graduated from their classes. Following graduation, Hank was offered a position with the Brand Corporation. Charles and his X-Men bid the Beast farewell as he went on to a new life. Shortly thereafter, Hank accidentally mutated himself further into a more bestial form, a transformation he kept secret from everybody, including Charles and the X-Men. Also unknown to all at the time the Brand Corporation was a target of the Secret Empire.
Not long after this, Charles old colleague Hans Jorgenson had been kidnapped and that Spider-Man was being blamed. Charles sent the X-Men out to find Spider-Man. The group soon learned that Spider-Man was not responsible for the kidnapping, but was seeking out Jorgenson to help cure him of an mystery illness plaguing him. The X-Men and Spider-Man soon discovered that Jorgenson was kidnapped by Spider-Man's foe Morbius the Living Vampire and rescued him. Xavier and Jorgenson worked to cure Spider-Man of his illness using the enzymes in Morbius' blood. Charles then contained Morbius at the mansion for a time. When the Angel became worried about Hank, Charles refused to get involved, but did not stop Warren from seeking out his friend. In tracking down the Beast, Angel learned of his friend's further mutation and reported it back to the X-Men. Not long after this the Beast was also captured by the Secret Empire. Magneto resurfaced shortly thereafter and attacked the X-Men directly, incapacitating the group and using his magnetic powers to enslave Charles and most of the X-Men. Magneto then lured the Avengers into a trap, capturing the Scarlet Witch, Captain America, and Iron Man in the process. Unknown to anyone at the time the Angel was captured by the Secret Empire during this attack. The captive X-Men and Avengers were later rescued by the uncaptured Avengers along with the Black Widow and Daredevil. In the aftermath of the battle Charles and his students began trying to learn what happened to the Angel. With mutants still going missing, Charles assigned Cyclops, Iceman and Marvel Girl to check in on their various allies and enemies. Iceman went missing shortly thereafter. Not long after this, Charles and Cyclops were unable to stop Morbius from breaking free and escaping the mansion.
Taking a more proactive approach, Charles joined Cyclops and Marvel Girl in a search for their missing allies. Their search took them to the southwest where they encountered the Juggernaut in the middle of a battle with the Hulk. Professor X and his students incapacitated the Juggernaut and allowed the Hulk to go free before resuming their search. They tracked their old ally the Banshee down to Nashville, where they found him in the middle of a battle with Captain America and his partner the Falcon. Believing that the X-Men, Cap and Falcon were out to capture him, the Banshee fled the scene. Charles soon learned that Captain America and Falcon were also seeking to stop the Secret Empire and an alliance was formed. The heroes were soon attacked by Nick Fury and a team of SHIELD agent. Charles used his mental powers to shield his presence to keep his ties with the X-Men a secret and they made a hasty escape. Comparing notes, Charles suggested they try and determine the connection between the Secret Empire and the Beast's girlfriend Linda Donaldson who Charles tracked to the area. Cyclops then staged an attack on her while a disguised Cap and Falcon came to her rescue, posing as men seeking work. She quickly offered them a job, revealing herself as an agent of the Secret Empire, and they were hired to steal an electro-gyro from the Brand Corporation. This theft was a success and when Cap and Falcon were taken to the Secret Empire's secret hideout, Charles and his remaining students followed.
However, the plan went awry as the Secret Empire saw through the deception and attempted to capture Cap and the Falcon, Charles and his students came to their rescue. The heroes soon found the captured X-Men as well as Blob, Unus, Mastermind and Mesmero were also prisoners and that the Secret Empire was using their mental energies to power a weapon. Before the captured mutants could be freed the Secret Empire seemingly slew heroes with an atomic annihilator weapon. However the Empire had been infiltrated by SHIELD agents Gabe Jones and Peggy Carter who were controlling the cannon and fired a non-lethal blast. Getting X-Men and the others to cover, they regrouped and battled the Secret Empire when they attempted to storm the White House. While the X-Men freed their allies and defeated the Empire, Cap exposed their leader as a high ranking government official who committed suicide rather than face capture.
Charles soon became aware of a mutant signature on the island of Krakoa,  and had his X-Men reunited and sent on a mission to investigate the island. In the interim, Charles became aware that Magneto had resurfaced and reformed his Brotherhood of Evil Mutants. Seeking assistance, he contacted Doctor Strange's loose-knit team the Defenders to assist him in stopping Magneto. Tracking the Brotherhood to a secret cave, the Defenders and Charles were captured and witnessed as Magneto created a being he dubbed Alpha the Ultimate Mutant. The Brotherhood fled with the rapidly evolving Alpha and attacked the United Nations Building. Charles and the Defenders followed after them. During the course of the battle, Alpha reached the zenith of his evolutionary transformation and decided to use his vast intellect to judge whose ideologies were the most righteous. Alpha judged in favor of the heroes and Magneto and his Brotherhood were all reverted into children before Alpha left Earth to explore the universe. Charles then turned Magneto and his infantile Brotherhood over to Moira MacTaggart at her mutant research center to be re-educated in the hopes they would grow to be peaceful mutants.
Meanwhile, the X-Men arrived on Krakoa and realized that the entire island was actually a massive mutant form. The creature attacked them out right and captured them, cutting off their connection with Professor X. Xavier sought out Moira and asked her to allow him to use her students to rescue his team of X-Men. Moira reluctantly allowed this when Kid Vulcan and the other students agreed to help Charles. In order to fast track their training, Charles put them through a virtual training with his mental powers, giving these students months of training in just hours. Before sending these novice X-Men on their mission to save the others, Charles revealed to Kid Vulcan that he had discovered that Cyclops was his brother. These new X-Men proved to be no match for the island of Krakoa, and only succeeded in freeing Cyclops, sending him away while the group seemingly sacrificed their lives to cover his escape. When Cyclops returned to the Mansion and told Charles what happened, Xavier realized the grave error he made. Not wishing Scott to live with the grief of losing the brother he never knew, Charles erased all memory of this novice group of X-Men from the minds of Cyclops and Moira and began planning another rescue mission. To this end, Charles altered Scott's memories to make him believe that Krakoa released him in order to lure more mutants to the island to feed off their mutant energies.
Charles then gathered various mutants from around the globe to help rescue the captured X-Men. The new recruits included former allies Banshee, and Sunfire, as well as mutants the X-Men previously met such as the African weather controlling mutant Ororo Munroe later called Storm, and Logan who was the Canadian government operative known as Wolverine. Charles also recruited previously uninitiated mutants such as the Piotr Rasputin (codenamed Colossus) who could turn into organic steel, teleporter Kurt Wagner (codenamed Nightcrawler), and the superhumanly strong Native American John Proudstar (codenamed Thunderbird). This new team of X-Men proved more successful, rescuing the original team, and defeating Krakoa by jettisoning the island out into space. Charles used his mental powers to cover up the apparent death of Kid Vulcan's entire team, a shame that Charles kept secret for years. Upon their return from their mission, Charles invited everyone to remain with the X-Men, however most of the original team -- save for Cyclops -- left to pursue their own lives. Sunfire also decided to depart from the group, having no desire to be part of the team, having only agreed to help Xavier free the X-Men. Storm, Colossus, Wolverine, Banshee, Nightcrawler and Thunderbird all agreed to stay. Soon Charles and Cyclops began training this new generation of X-Men, who would become legends in their own right.
- First X-Men #1
- Uncanny X-Men Vol 3 #1
- All-New X-Men #1
- X-Men #1
- For a full history of the events that led to Charles Xavier deciding to found his school, refer to the entry on Charles Xavier's academic and military careers as well as his time in Israel
- X-Men: Legacy #208
- X-Men #20
- Uncanny X-Men #309
- X-Men: Deadly Genesis #5
- Bizarre Adventures #27
- Classic X-Men #43
- X-Men: The Wedding Album #1
- X-Men Origins: Jean Grey #1
- Classic X-Men #42
- X-Men Origins: Cyclops #1
- Marvel Saga the Official History of the Marvel Universe #1
- Uncanny Origins #2
- X-Men Vol 2 #-1
- X-Men #38
- Uncanny Origins #1
- X-Men: Odd Men Out #1
- X-Men #39
- X-Men #40
- X-Men #41
- X-Men #42
- Angel: Revelations #4
- Angel: Revelations #5
- X-Men #44
- X-Men Origins: Iceman #1
- X-Men #45
- X-Men #46
- X-Men #55
- Uncanny Origins #3
- X-Men #56
- X-Men #15
- X-Men #51
- Uncanny Origins #6
- X-Men Origins: Beast #1
- X-Men #52
- X-Men #53
- X-Men Origins: Beast #1: This account seems to be more accurate given the Conquistador was seen alive and well many years later in Marvel Zombies 3 #1
- X-Men: Legacy #216
- Marvel Comics Presents #85
- Marvel Comics Presents #88
- X-Men Origins: Emma Frost #1
- Uncanny X-Men #300
- Official Handbook of the Marvel Universe Master Edition #23
- X-Men First Class #1
- X-Men #2
- Tales of Suspense #49
- Avengers #3
- Sentry/X-Men #1: The X-Men were forced to forget the existence of the Sentry as per the events of Sentry #1
- X-Men #3
- Thor Corps #3: This time disruption was caused by Demonstaff who was later defeated by the Thor Corps in Thor Corps #4
- X-Men #4
- X-Men: Legacy #209
- Avengers Origins: The Scarlet Witch & Quicksilver #1
- Avengers #234
- X-Men #5
- Fantastic Four #28
- Unlimited Access #3
- Unlimited Access #4
- X-Men #6
- Journey into Mystery #109
- Excalibur XX Crossing #1: Excalibur earned the ire of Dr. Doom in Excalibur #37 through 39
- X-Men #7
- X-Men #8
- Untold Tales of Spider-Man #21
- Untold Tales of Spider-Man Annual #1997
- X-Men #9: Lucifer crippled Charles while he traveled through Tibet a number of years before he formed the X-Men, as depicted in X-Men #20
- X-Men: Gold #1
- Fantastic Four #36
- X-Men #10
- X-Men First Class #2
- X-Men First Class Vol 2 #10
- X-Men #11
- X-Men First Class #7
- X-Men #12
- X-Men #13
- X-Men #32
- X-Men #14
- X-Men First Class #6
- X-Men First Class #8
- X-Men First Class Vol 2 #9
- X-Men First Class #5
- X-Men First Class Vol 2 #2
- X-Men First Class Vol 2 #3
- X-Men Forever #3
- Fantastic Four Annual #3
- Marvel: Heroes & Legends #1
- Marvels #2
- X-Men #16
- X-Men #17
- X-Men #18
- X-Men First Class Vol 2 #12
- X-Men First Class (Vol. 2) #13: Agent Baker turned out to be a Skrull spy as revealed in X-Men First Class Special #1.
- X-Men First Class Vol 2 #14
- X-Men First Class (Vol. 2) #15: Medusa is the member of the Inhumans. She was originally found by the Wizard with amnesia and recruited into the Frightful Four in Fantastic Four #36. This story takes place after the Frightful Four were defeated by the Fantastic Four in Fantastic Four #43. Medusa eventually regains her memories and rejoins in the Inhumans in Fantastic Four #44. The reason Angel returned to the X-Men was because he was going to be placed in an arranged marriage if he remained in the Valley of Mist.
- X-Men First Class Vol 2 #1
- X-Men First Class Vol 2 #16
- X-Men #19
- Marvel Comics Presents #59
- X-Men #21
- X-Men First Class Vol 2 #5
- X-Men #22
- X-Men #23
- X-Men #24
- X-Men First Class #3
- X-Men #25
- X-Men #26
- X-Men #27: the Scarlet Witch and Quicksilver joined the Avengers in Avengers #16. At the time of this story they were on a leave of absence in their native Transia because they believed their powers were fading due to the time they had spent away from their homeland, as revealed in Avengers #30. Spider-Man refused to join the X-Men after a disastrous attempt to join the Avengers as seen in Amazing Spider-Man Annual #3
- X-Men #28
- X-Men #29: The Super-Adapatoid went into hiding after it erroneously believed slew Captain America in Tales of Suspense #84. It would later be reactivated by AIM in Avengers: Earth's Mightiest Heroes (Vol. 2) #1. Mimic's powers eventually returned as revealed in Incredible Hulk #161
- X-Men #30
- X-Men #31
- X-Men Unlimited #42
- X-Men #33
- X-Men #34: This was temporary and both Tyrannus and the Mole Man's memories eventually returned as explained in X-Men: The Hidden Years #21
- X-Men #35
- X-Men #36
- X-Men #37
- X-Men First Class #4
- X-Men First Class Special #1
- X-Men #65
- X-Men #40: This story suggests that the Frankenstein's Monster featured in Mary Shelly's Frankenstein was really an alien robot. However it was later revealed that in the Earth-616 universe the Frankenstein's Monster really existed as clarified in Silver Surfer #7
- X-Men #43
- Avengers #53: Magneto survived this blast as revealed in X-Men #63 as he was washed away to the Savage Land.
- Domination Factor: Avengers #2.4
- X-Men #47
- X-Men #48
- X-Men #49
- X-Men #50: This was not the true Magneto but an android, as revealed in X-Men #58. The Magneto android and the Demi-Men army that Mesmero commanded were created by Samuel Saxon, later the Machinesmith. This was never depicted but stated in Official Handbook of the Marvel Universe #7 and other subsequent Marvel Handbooks.
- X-Men #52: While these documents revealed that Lorna Dane's biological parents were Suzanna and Arnold, it turns out that Mesmero's claims were actually correct. As X-Factor #243 later revealed, Lorna's mother Suzanna had an affair with Magneto, becoming pregnant with Lorna. Suzanna attempted to hide this from her husband, hence the incorrect birth records. The plane crash that killed her parents that is referenced in X-Men #52 was revealed to have been caused Arnold as seen in X-Factor #243 when he learned of his wife's infidelity.
- Avengers #60
- Avengers: Earth's Mightiest Heroes Vol 2 #6
- X-Men #53: Blastaar was really shunted back into the Negative Zone as seen in Incredible Hulk #113
- X-Men #54
- X-Men #55: It was later revealed in Uncanny X-Men #376 that Living Pharaoh's powers were tied to Alex Summers thanks to the genetic manipulations of Mister Sinister. The purpose was to used the Pharaoh as an energy battery to channel energy into an ascension machine built by Sinister for his master Apocalypse for a ritual called The Gathering of the Twelve which would happen many years later.
- X-Men #57
- X-Men #58
- X-Men #59
- X-Men #60
- X-Men #61: X-Men #114 and X-Men: The Hidden Years #6 revealed that Lykos survived the fall and sought refuge in the Savage Land
- X-Men #62: Magneto is not recognized here because he is not wearing his trademark costume and helmet. The costume that he gives Angel is a means to siphon his mutant energies and boost Magneto's then failing powers as revealed in Avengers #111
- X-Men #63: Magneto of course survived this defeat as well. As depicted in X-Men: The Hidden Years #4 the ground under him gave way and he was swept away in an underground river ending up in the realm of the Nhu’Ghari
- X-Men #64: This story states that Sunfire's mother was a survivor of the bombing of Hiroshima while pregnant with Sunfire. This radiation caused Shiro to gain his mutant powers. Even Official Handbook of the Marvel Universe A-Z #11 states this. However per the Sliding Timescale of Earth-616 as the modern age slides forward it will be impossible that Shiro's mother could have been present and survived the atomic bomb blast during World War II without drastically aging the character. Short of an official explanation this should be considered a topical reference. As such it could be logically assumed that while Sunfire was avenging the nuclear bomb drops of World War II, the very personal reason can be ascribed to a relative as opposed to his mother.
- X-Men #107
- X-Men #66
- X-Men: The Hidden Years #1
- X-Men / Spider-Man #1: Unknown to anyone at the time Kraven was hired by Mister Sinister to lure the X-Men into a trap so that he could collect their DNA. This was part of a long running scheme that eventually led to the creation of Xraven, a clone of Kraven with all the powers of the original X-Men as seen in X-Men / Spider-Man #4
- Fantastic Four: World's Greatest Comics Magazine #3
- Fantastic Four: World's Greatest Comics Magazine #4
- Fantastic Four: World's Greatest Comics Magazine #10
- Fantastic Four: World's Greatest Comics Magazine #11
- Fantastic Four: World's Greatest Comics Magazine #12
- X-Men (Vol. 2) #94: The X-Men captured the Sentinel ships at the end of X-Men #59
- X-Men: The Hidden Years #2
- X-Men: The Hidden Years #3: The volcanic gas in the region of caused low level telepathy and had healing property that rendered the Nhu'Ghari immortal. However over the centuries it caused them to mutate into their avian forms. They began posing as gods and tricking local tribes into bringing their dead and dying to their domain to be healed and used as slave labor.
- X-Men: The Hidden Years #4
- X-Men: The Hidden Years #5
- X-Men: The Hidden Years #7
- X-Men: The Hidden Years #8
- X-Men: The Hidden Years #9: The Phoenix Force would return to Jean in X-Men #101 while trying to returned the X-Men to Earth from a mission in space.Fantastic Four #286 revealed that Jean was put in suspended animation while the Force took her form for a time.
- X-Men: The Hidden Years #10
- X-Men: The Hidden Years #11
- X-Men: The Hidden Years #13
- X-Men: The Hidden Years #14
- X-Men: The Hidden Years #14: Bert Worthington became the Dazzler in Ka-Zar #2 an slew Warren's father Warren Worthington Jr.. Angel seemingly slew Dazzler in Marvel Tales (Vol. 2) #30
- X-Men: The Hidden Years #15
- X-Men: The Hidden Years #16: As per Marvel: The Lost Generation #12 Yeti was member of the First Line a group of heroes that predated the modern age of heroes. Yeti betrayed his teammates during an attempted Skrull invasion of Earth that led to the demise of that team.
- X-Men: The Hidden Years #17
- X-Men: The Hidden Years #18
- X-Men: The Hidden Years #19
- X-Men: The Hidden Years #20: This story takes place at the same time as Fantastic Four #102
- X-Men: The Hidden Years #21: This story takes place at the same time as Fantastic Four #103
- X-Men: The Hidden Years #22: This story takes place at the same time as Fantastic Four #104
- X-Men First Class Vol 2 #4
- Incredible Hulk #150
- X-Men First Class Vol 2 #6
- X-Men First Class Vol 2 #7
- X-Men First Class Vol 2 #8
- X-Men First Class Vol 2 #11
- X-Men: Deadly Genesis #1
- X-Men: Deadly Genesis #2
- X-Men: Deadly Genesis #3
- X-Men: Deadly Genesis #4
- X-Men: Deadly Genesis #5: This story contradicts the events of X-Men Origins: Emma Frost #1 in that the Emma Frost who meets Charles and Moira MacTaggart at the Hellfire Club acts as though she is meeting them for the first time, and also is apparently unaware that she is a mutant. It could be presumed that Charles wiped her memories after his previous failed attempt to recruit her in X-Men Origins: Emma Frost #1, certainly the events of X-Men: Deadly Genesis would support that erasing memories was not something Charles was opposed to during this long period.
- X-Men: First Class Giant-Size Special #1: This story revealed that Agent Baker was a Skrull, part of an early run for for their Secret Invasion of Earth.
- X-Men: First Class Finals #1
- X-Men: First Class Finals #2
- X-Men: First Class Finals #3
- X-Men: First Class Finals #4
- Amazing Adventures Vol 2 #11
- Marvel Team-Up #4: Spider-Man's occurred when he tried to cure himself of his spider powers in Amazing Spider-Man #100 & Amazing Spider-Man #101. Instead of curing himself he grew four extra arms. Spider-Man reversed this mutation using some of Morbius' blood in Amazing Spider-Man #102. It was the enzymes in this blood that was threatening Spider-Man's life in this story.
- Amazing Adventures Vol 2 #15
- Captain America #173
- Avengers #110
- Captain America #174
- Avengers #111
- Fear #20
- Incredible Hulk #172
- Captain America #172: At the time Captain America was framed for murder by the Secret Empire as part of a plot to take over America starting in Captain America #170
- Captain America #173: Linda Donaldson began romancing Henry McCoy in Amazing Adventures (Vol. 2) #11 as part of her mission as a spy for the Secret Empire to steal the Brand Corporation secrets.
- Captain America #175: This story makes numerous references to the Watergate scandal and heavily suggests that the leader of the Secret Empire was resigned US President Richard Nixon. These should be considered topical references relevant to the time of publication and are subject to the Sliding Timescale. Subsequent references to this story in Avengers: Forever #2 generalizes the Secret Empire's leader to a "high ranking government official".
- Marvels: Eye of the Camera #2
- Giant-Size X-Men #1
- Marvel Team-Up #23
- Defenders #15
- Defenders #16
- X-Men #112 confirmed Magneto was incarcerated at Muir Island, while the rest of the Brotherhood were not confirmed as being held there until Champions #17
- X-Men: Deadly Genesis #6: Charles learned that Kid Vulcan was the brother of Cyclops due to their similar mental patterns. He would not know until years later that Kid Vulcan was the unborn child of Christopher and Katherine Summers who was harvested from Katherine's dead body after they were captured by the Shi'ar years ago. Gabriel was artificially aged and made a slave of Davan Shakari, a Shi'ar spy active on Earth until he eventually escaped many years later. While Petra and Sway were killed by Krakoa, Kid Vulcan and Darwin survived thanks to Darwin's powers. Darwin absorbed his comrades powers and merged with Vulcan, pulling him below the surface of Krakoa where they remained in stasis for years.
- Giant-Size X-Men #1: Although this story indicates that this was the first time Charles contacted many of these new X-Men, various tales reveal that this is not the case. Charles first met Storm when she was a young pickpocket in Cairo, Egypt per X-Men #117 a fact that Charles did not realize until some time after Storm joined the X-Men. It was also implied that Charles was attempting to track her down after he formed the X-Men in X-Men First Class #8. Charles original students also encountered Storm on their own in X-Men: The Hidden Years #5 through 8. Wolverine apparently met Charles on two --albeit conflicting-- occasions. The earliest was in First X-Men #1 taking place when Charles was still at Oxford University. At that time Logan was recruiting his own team of mutants, which Charles refused to join.Excalibur (Vol. 3) #14 states that Logan fought with Charles during the time in the military, however this was contradicted in the First X-Men series which states that Logan was still gathering mutants while Charles was in the military. Wolverine's inability to recognize Xavier in Giant-Size X-Men #1 is due to various memory losses as a result of his own mutant powers (as first implied in Wolverine: The Origin #1 and later in Wolverine: Origins #1) and more recently thanks to the memory implants and manipulations of the Weapon X Project as seen in Marvel Comics Presents #72 through 84. Charles was revealed to know about the other members of this new team of X-Men many years earlier per the flashback in Uncanny X-Men #300
- Classic X-Men #1
- X-Men: Deadly Genesis #6: The only record of Kid Vulcan's was a recording that Moira MacTaggert made before Charles wiped her mind as revealed in that issue. Moira never uncovered the recording as she later died in X-Men (Vol. 2) #108. When Kid Vulcan was awoken in X-Men: Deadly Genesis #1 the recording was later uncovered by Banshee.
- X-Men #94