An alien who plotted to conquer Earth used a costume to make himself appear human. Thus, he crafted the identity of the Mutant-Master, a mutant seeking to conquer humanity so that mutantkind could rule.
The Mutant-Master planned to cause an explosion within a high-level Russian meeting, knowing that the United States would be blamed. The workers at an American missile base would be gassed, and his agents would launch their nuclear weapons at Russia, leading to World War Three and the destruction of the human race. In the carnage that remained, with these two major world powers destroyed, a third group, Factor Three, would seize power.
The Mutant-Master learned of a mutant metamorph and followed his trial to the house of Jack Bolton, which was occupied by the mutant metamorph, who had taken Bolton's form. Using a report on Bolivar Trask's Sentinels, the Mutant-Master convinced the metamorph that humanity saw mutants as a threat and would try to destroy them, and that mutant-kind should rule the world. Naming the metamorph the "Changeling," the Mutant-Master convinced him to accept the role of his second-in-command in Factor Three, where he would handle his day-to-day operations. The Changeling then recruited the Blob, Mastermind, Unus and the Vanisher from among the X-Men's greatest enemies to serve as their fighting force, as well as the operative Ogre.
The Mutant-Master sent the Ogre and the Vanisher to ambush Humus Sapien, placing a control helmet on him to inhibit his power. He then sent the Ogre and Banshee to abduct Professor X, who detected the mutant members of Factor Three (see comments).
The Ogre located the secret headquarters of the X-Men. Though the Ogre nearly succeeded in their first attempt, both Banshee and Ogre were captured by the X-Men, and the Banshee revealed how he had been forced to serve Factor Three via the explosives in his headband. Professor X mentally disabled the explosives, allowing the removal of the headband and freeing Banshee from Factor Three's servitude. The Banshee told them that Factor Three was the most dangerous secret organization on the Earth, and that they had the means to conquer the world or even to destroy it.
After escaping, the Ogre returned to Factor Three, only to be chastised by the Mutant-Master for his failure, and instructed to wait at Factor Three's Mt. Charteris base until the Mutant-Master could return to deal with him further.
Meanwhile, the Banshee started a weeks-long search of the mountains and valleys of Central Europe for the base of Factor Three. He was aided by advanced detection equipment given to him by Professor X. Professor X locked himself in a room and shut off his thoughts to the outside world while he focused on researching Factor Three, but was pulled from his research by the Warlock (later Merlin Demonspawn). After the Warlock was defeated, Professor X reminded the X-Men of the threat of Factor Three.
Before long, Cerebro failed to detect any more emissaries of Factor Three in the USA. Telling the X-Men about Cerebro's findings (or lack thereof), Professor X gave them the weekend off. After they departed, he resumed his vital experiments, pausing only to notify the other X-Men after receiving a mental message from Cyclops.
Completing his experiments, Professor X attempted to restore the Juggernaut, whom he had rendered inert in their last battle. Professor X began to use his Energo-Transformer to drain the Juggernaut's power so he could then cure his embittered mind. However, as he did so, he sensed a new, powerful alien force entering the Juggernaut's mind, adding to his own natural resistance. As a result, the device was destroyed, and the Juggernaut instead gained Professor X's telepathic powers, rendering X unconscious. The Juggernaut subsequently overpowered the X-Men, but as he prepared to destroy their school and bury them under it, he was telepathically contacted by Factor Three. They revealed that they had caused the explosion which freed the Juggernaut and instructed him to leave the X-Men behind, steal a jet to Europe, and join them. Though irritated at being commanded, the Juggernaut nonetheless decided to follow their instructions. He wished to add their power to his so that they could conquer the world.
As the Juggernaut continued on his mission to steal a ship to travel to Factor Three's European base, Cyclops and Marvel Girl, learning of Xorak the Outcast - a resident of the Crimson Cosmos accessed via the Crimson Ruby of Cyttorak - used a mystic spell to access the Ruby and defeat Xorak, pulling the Juggernaut within the Ruby as well. However, while the X-Men were battling the Juggernaut, android agents of Factor Three entered the X-Mansion and kidnapped Professor X. The androids wrecked Cerebro as well before departing the X-Mansion to prevent the X-Men from easily locating Professor X.
As Factor Three continued to hold Professor X captive, the Banshee located Factor their secret sanctuary. On approaching, he was assaulted by one of its Arachnoids (mechanical spiders), narrowly surviving its paralysis ray. Banshee fled to the nearby chalet he had rented and used the equipment given to him by Professor X to contact the X-Men. However, just as he began to send his message, he collapsed from the effects of the paralysis ray. Only his message to "Beware the Spider" went out. No sooner had Banshee collapsed when Factor Three's android Agents 10 & 14 entered his chalet, and they easily captured the unconscious mutant. The androids reported his capture to the Changeling, who sent some of his Arachnoids to the USA to learn how much the Banshee had managed to tell the X-Men. Traveling in a Magno-Disk (which they called a Gravo-Disk), they brought the Banshee back to Factor Three's base.
The Arachnoid arrived in Westchester county via a Magno-Disk, where it was observed by Peter Parker, who was out on a relaxing motorcycle ride. As Spider-Man, Parker investigated, encountering the Arachnoid, which attacked him. Spider-Man destroyed the Arachnoid, but the energies released during their battle were detected by Cerebro and reported as a mutant presence. The X-Men investigated, and--based on the Banshee's message--initially assumed Spider-Man to be the threat. After a brief battle, Spider-Man revealed the Arachnoid that he had fought. Cyclops pondered the question of whether a robot built by a mutant might register on Cerebro's sensors as a mutant.
Meanwhile, Marvel Girl found a note in Professor X's files reporting the communications crystal within the Banshee's helmet. She tried to contact him to no avail as he remained unconscious. Nonetheless, she was able to track his location to a Central European mountain range. When the X-Men returned, they decided to follow the trail to try to locate Professor X and defeat Factor Three. Determining that Factor Three's base was located in the Alps, the X-Men learned that their jet was out of fuel, and they realized that none of them had the money to refill it. While they tried to come up with the money somehow, they encountered and defeated Mekano, after which Mekano's grateful father lent them the money for five plane tickets to Central Europe. Shortly thereafter, the five X-Men boarded the plane, unaware that their every move was watched by the Changeling from within Factor Three's hollow mountain base in Central Europe.
The Changeling studied tapes of the X-Men's victories over the Juggernaut as their plane approached. He dispatched Magno-Disk One after them, and it began assaulting the jet bringing them to Europe. Realizing that they were the targets of the assault and that they were thus endangering the other passengers' lives, the five X-Men bailed out. Cyclops destroyed the Magno-Disk with an optic blast, and the X-Men managed to land safely. They defeated the first Arachnoid that confronted them, but a pair of androids then sent two more Arachnoids after them. The X-Men ultimately fell before the Arachnoids' gas attack, and were captured by Factor Three and placed within a force field. The Blob, Mastermind, Unus, and the Vanisher revealed themselves as members of Factor Three and condemned the X-Men as traitors to the mutant race. The Changeling and Mutant-Master then appeared as well, and the Changeling explained that they would be placed on trial with himself as prosecutor; the Mutant-Master told them that the penalty for their actions would be death.
The Blob, Mastermind, Unus, and the Vanisher reviewed how the X-Men had opposed them in the past, and the Changeling asked the Mutant-Master to sentence them to death. Before pronouncing his verdict, the Mutant-Master revealed how Factor Three would achieve world domination. He then instructed the Changeling to subject the X-Men to his Oblivio-Ray. After being stunned by an energy blast, the five mutants were hooked into the Oblivio-Ray, intended to sap their wills and make them susceptible to the Mutant-Master's command. The Mutant-Master arranged things so that the X-Men would be able to get free to try to stop his plans, hoping that the military would blame the X-Men for the intended attacks in case his plans were thwarted.
As the Oblivio-Ray was activated, the rest of Factor Three left, and the Iceman formed icicles which melted to short out the equipment, allowing them to escape. One of Factor Three's robots attacked them, but they destroyed its sensory circuits, sending it off on a blind rampage. The X-Men tried to stop the Changeling and Mutant-Master, but found they had already departed. However, the Mutant-Master then appeared to them on a view-screen, telling them that they would be too late to stop his plan from coming to fruition. The Blob and Vanisher were sent to Russia, while Mastermind and Unus were kept on standby.
The X-Men narrowly escaped in a pair of Magno-Disks as the Mutant-Master blew up Factor Three's European base. From within another base, the Mutant-Master assured the Changeling that the X-Men's escape would not threaten their plan. When questioned by the Changeling on how two fully-operational Magno-Disks had been left behind for the mutants to use, the Mutant-Master dismissed his concerns. Irritated, the Changeling told the Mutant-Master that he couldn't succeed without his aid, but the Mutant-Master silenced him with several near-misses from his mobile platform. The Mutant-Master then reminded the Changeling of his role as second-in-command. The terrified Changeling apologized, but the Mutant-Master continued to torment him with other weapons until he felt satisfied that the Changeling's loyalty had been ensured. The Mutant-Master then commanded the Changeling to check in on the Blob, ignoring his concerns that such a communication might be intercepted. After the Blob had reported that all was going as planned, the Mutant-Master dismissed the Changeling, who resented his treatment and began to wonder about his role following mankind's defeat. Meanwhile, the Mutant-Master gloated that none suspected his true goal, nor could they do anything about it even if they did.
Angel, Beast, and Marvel Girl traveled to the Russian base, fighting their way past security to confront the Blob, Vanisher, and several Factor Three minions. The X-Men defeated their foes, but the Vanisher teleported away, and the minions exploded, revealing themselves to be androids. The X-Men and the Blob were then captured at gunpoint by the Russians and thrown into a cell together. Cyclops and Iceman tried to warn the US troops about Factor Three's plans, but they were forced to fight their way out when the military tried to take them prisoner.
Meanwhile, the imprisoned Professor X tried to warn the Changeling that the Mutant-Master intended to betray him, but the Changeling slapped him and threatened to execute him if he did not remain silent. However, the Mutant-Master then appeared, telling the Changeling that only he decided who would live or die, and he dispatched the Changeling from the chamber. From within his base, the Mutant-Master gloated about his assured victory.
Becoming suspicious of the Mutant-Master due to increasingly eccentric orders, the Changeling checked his computers, learning that the war they were starting wouldn't just wipe out most humans, it would wipe out everything. The Changeling then freed Professor X and the Banshee from their restraints. Far away, within the American missile base, Cyclops and Iceman neutralized Factor Three's gas weapon and then fought off their agents, escaping back to their Magno-Disk under a cloud of steam. Back in the Russian base, the other X-Men broke free and located the bomb within a briefcase. The Blob grabbed the briefcase, intending to allow it to explode as he figured his body would be unharmed; Marvel Girl convinced him that the Mutant-Master might have made the bomb powerful enough to harm even him, in order to prevent him from talking in the event of capture. The Angel disposed of the bomb in time, and the Russians began to suspect that the Americans had truly saved them.
Back within his floating sphere-base, the Mutant-Master was astounded that his plans had been foiled. As he began to wonder where the Changeling was, Cyclops and the X-Men (guided by their Magno-Disks), entered the base and confronted the Mutant-Master. He protected himself from their attacks with a force field until Mastermind, Unus, and the Vanisher returned, though the remaining X-Men then arrived as well. Before the two groups of mutants could begin their fight, the Changeling appeared in the form of Professor X, and he warned them all that the Mutant-Master was the true enemy. The Mutant-Master tried to convince his allies that Professor X was lying, but Professor X showed that the Mutant-Master had deliberately allowed the X-Men to escape when they were at his mercy. The Mutant-Master moved to strengthen his force field, which the others mistook as an attack, and so he abandoned his alliance and attacked the group, forcing them back with his shield and sending his androids to battle them.
As the mutants fought the androids, the Banshee recovered and used his sonic scream to shatter the androids, and the metal costume of the Mutant-Master was destroyed as well, revealing the green, tentacled alien beneath it all. The alien commanded the others to stop, but he was weakened by the Banshee's scream, and Unus battered him as well. Unwilling to accept defeat, Mutant Master killed himself using a device that caused an explosion in his brain.
A robotic exoskeleton that made him appear human
- 5 appearance(s) of Mutant Master (Earth-616)
- 2 minor appearance(s) of Mutant Master (Earth-616)
- 10 image(s) of Mutant Master (Earth-616)