- X-Men (Main story and flashback)
- Cyclops (Scott Summers) (First appearance chronologically) (Joins team)
- Mystique (Raven Darkholme) (Main story and flashback) (Rejoins team) (Impersonates Psylocke)
- Nightcrawler (Kurt Wagner) (First appearance) (Joins team)
- Jean Grey (Joins team)
- Beast (Hank McCoy)
- Professor Charles Xavier (Main story and flashback)
- Storm (Ororo Munroe) (First appearance chronologically) (Joins and leaves Horsemen of Apocalypse) (Joins team)
- Quicksilver (Peter Maximoff) (Joins team)
- Havok (Alex Summers) (Death)
- C.I.A. (Only appearance)
- Weapon X (Logan) (First appearance as Weapon X) (Last appearance)
- Apocalypse (En Sabah Nur) (Only appearance; dies)
- Horsemen of Apocalypse (1983) (Only appearance) (Disbands)
- Weapon X Program (Only appearance) (Unnamed)
- Colonel William Stryker Jr. (Last appearance)
- Horsemen of Apocalypse (3600, B.C.) (Disbands)
- Richard Nixon (Mentioned)
- Blob (Fred Dukes) (Only appearance)
- Milosz (Only appearance)
- Magda (Only appearance; dies)
- Nina (Only appearance; dies)
- Clan Akkaba (First appearance)
- Erik's Father (Mentioned)
- Mr. Summers (Only appearance)
- Mrs. Summers (Only appearance)
- Xavier Institute student body
- Jakob (Only appearance; dies)
- Kevin MacTaggert (Photo)
- Ronald Reagan (Appears on a computer screen, TV, or hologram only) (Topical reference)
- Pope John Paul II (Appears on a computer screen, TV, or hologram only) (Topical reference)
- Caliban (Only appearance)
- Edie Lehnsherr (Only in flashback)
- Klaus Schmidt (Only in flashback)
- Ms. Maximoff (Last appearance)
- Stan Lee (First appearance) (Cameo)
- Banshee (Sean Cassidy) (Only in flashback)
- Essex Corporation (First appearance)
- Dr. Nathaniel Essex (Behind the scenes)
Races and Species:
- Earth-TRN414 (Main story and flashback)
- Earth (Main story and flashback)
- Egypt (First appearance)
- United States of America
- New York
- East Germany (First appearance)
- East Berlin (First appearance)
- Poland (First appearance)
- Canada (First appearance)
- Cuba (First appearance) (Only in flashback)
- Australia (First appearance)
- Sydney (First appearance)
- Earth (Main story and flashback)
- Cerebro (destruction)
- Magneto's Helmet
- Cyclops' Visor (First appearance chronologically)
- Ruby Quartz (First appearance chronologically)
- Ruby-Quartz Sunglasses (First appearance chronologically)
- Holocaust (Mentioned)
In 3600 BC, En Sabah Nur, an incredibly powerful mutant and the first of his kind, ruled ancient Egypt. Although worshiped as a god by his followers, En Sabah Nur's body grew old, so he planned to transfer his consciousness into the body of another mutant whose regenerative healing factor will effectively make him immortal. During the transfer ritual, some of En Sabah Nur's human followers betray him, trapping him and his Four Horsemen inside his pyramid. One of the Horsemen is able to shield her god from falling debris before she dies. The rubble encases En Sabah Nur underground, where he lays dormant for thousands of years.
In 1983, CIA Agent Moira MacTaggert is in Cairo tailing one of the many mutant-worshiping cults that sprung up after the public became aware of the existence of mutants when she accidentally revives En Sabah Nur. The ancient mutant's return is signaled by a tremor felt all over the world. En Sabah Nur wanders the streets of Cairo, eventually coming across Ororo Munroe, a mutant using her powers to control the weather to aid a gang of young kids in petty crimes. Ororo takes En Sabah Nur back to her gang's hideout after he fights off a group of muggers threatening her. A poster of Mystique hangs on one of the hideout's walls, as Ororo sees her as a hero to mutants worldwide. En Sabah Nur places his hand on a television to learn about the state of the world he awoke in, and finds himself disgusted with the weak people allowed to rule the world. En Sabah Nur turns Ororo into the first of his new Horsemen by enhancing her abilities and giving her a new name - Storm.
In Poland, Magneto has taken to living a relatively normal life as a steelworker under the alias "Henryk Gurzky" with his wife Magda and daughter Nina. An accident at the steel mill prompts Magneto to use his powers to save a coworker, inadvertently outing himself as a mutant. That night, Magneto urges Magda that they need to leave immediately to avoid persecution, but they cannot find Nina. They eventually find her in the arms of police officers wielding archaic weapons. The police aren't wearing any badges, and the chief officer holds up a newspaper clipping of Magneto's attack on Washington, D.C. a decade ago to reveal they know exactly who "Henryk Gurzky" really is. Magneto turns himself over to the police in exchange for his daughter's freedom. Nina loses control over her mutant abilities to empathically communicate with wildlife, resulting in a swarm of birds attacking the police. One of the officers accidentally lets loose an arrow that impales both Nina and Magda. The police let Magneto go to hold the dead bodies of his wife and daughter. Magneto sends Nina's metal locket through the necks of the police officers.
Meanwhile, Mystique - while disguised in an inconspicuous form - investigates an underground, illegal mutant fighting ring in East Berlin. She witnesses a fight between the winged mutant Angel and Kurt Wagner, a blue-skinned mutant with a demonic appearance and teleportation abilities known as "Nightcrawler." An electric current running through the steel cage surrounding the ring prevents Kurt from using his powers to escape. The armed guards surrounding the ring try to force Kurt into fighting Angel when he shows a reluctance to do so, giving Mystique the distraction she needs to overload the building's electric systems. Before the power shuts down, one of Angel's wings comes into contact with the electrified cage, badly damaging it to the point he can no longer use it to fly. Mystique grabs Kurt when he teleports out of the ring, and the two of them teleport away from the ring to escape the confusion inside. She takes him to see Caliban, a mutant black marketeer who can provide Kurt with a fake I.D. he can use to leave the country. Caliban tells Mystique about what has happened to Magneto, compelling her to go to the United States to get help from Charles Xavier in stopping Magneto's next rampage before it gets worse.
Alex Summers takes his younger brother Scott to see Professor Xavier after his mutant powers violently manifest at school. Scott's mutant abilities are similar to Alex's in that he can generate powerful blasts of energy; however, Scott's energy comes out of his eyes, and he has no way to stop it other than to close his eyes. In the ten years since their battle with the Sentinels, Xavier has transformed his mansion into a school where young mutants can learn to control their powers. Scott (who can't see) bumps into Jean Grey, one of Xavier's students and an immeasurably powerful psychic. That night, the tremor created by En Sabah Nur's return gives Jean a powerful vision of the world ending at his hands that Xavier assures her was only a nightmare. Jean's powers as they manifested in her sleep melted the wallpaper in her room.
The next morning, Xavier uses Cerebro to find the source of the tremor that gave Jean her vision. He traces it to Cairo, but instead of finding a mutant finds Moira MacTaggert. Xavier and Alex go to Langley to see Moira about what happened in Egypt. Charles erased her memories of him and her time with the original X-Men, so when they see her it is as if they are meeting for the first time. Moira tells them about En Sabah Nur, the first mutant, and how he had returned. While they are gone, Mystique and Kurt show up at Xavier's mansion to talk to Charles about Magneto. Kurt leaves with Jean, Scott (who Beast gave a special pair of sunglasses with quartz lenses that hold back his optic blasts), and Jubilee to go to the mall.
Meanwhile, En Sabah Nur and Storm seek out Caliban so he could lead them to other powerful mutants who could serve as his Horsemen. En Sabah Nur makes Caliban's psychic enforcer Pyslocke his second Horseman, and she leads them to Angel. Psylocke did not know that Angel could no longer fly, but En Sabah Nur replaces his bird-like wings with newer, metal ones that can throw his "feathers" like knives. En Sabah Nur and his Horsemen then teleport to Poland to recruit Magneto. They find him about to avenge his family by massacring his former coworkers at the steel mill who turned him in. En Sabah Nur kills them for Magneto by turning them into dust, and then takes them all to Auschwitz, where Magneto lost his family for the first time. The ancient mutant instructs Magneto to rip the camp's foundations out of the ground. As Magneto tears abandoned Auschwitz buildings to pieces, En Sabah Nur gives them their mission - to destroy the world ruled by false, weak gods, and from the ashes build a better one in his image.
Charles and Alex return to Xavier's mansion with Moira to figure out what to do about En Sabah Nur. After Charles has a quick word with Mystique, the two of them, Moira, Alex and Beast go to Cerebro so Charles could find Magneto and put an end to his rampage. En Sabah Nur senses Charles in Magneto's head and follows their psychic link back to Cerebro. He takes over Charles mind, and using Cerebro takes over the minds of the soldiers responsible for the world's stockpiles of nuclear weapons. He makes them all launch their nukes straight up into space to render them all useless against him. Xavier has Alex destroy Cerebro with his mutant powers to stop En Sabah Nur from taking over anyone else's mind.
They leave the burning Cerebro room only to find En Sabah Nur and his Horsemen teleported themselves into Xavier's mansion to kidnap Charles. Alex accidentally triggers an explosion in a failed attempt to prevent them from leaving with the professor. Just then, Peter Maximoff arrives outside the institute to speak with Xavier about Magneto. In the decade that passed since he helped break him out of the Pentagon, Peter discovered that Magneto is actually his father, and after he saw a news report about Magneto's resurfacing in Poland, hoped Charles Xavier would help him find him. Peter uses his speed to get everyone safely out of the house before it is destroyed. Scott, Jean, Kurt and Jubilee arrive back at the mansion just in time to see it blow up. Scott desperately looks for his brother, but he was the closest to the blast, and was engulfed by the fireball before Peter got everyone out. Mystique briefly loses control of her powers, revealing her true form to the students.
The U.S. military traced the psychic pulse that took over the soldiers to Xavier's mansion. A squadron of agents led by Colonel William Stryker land their helicopters near the outskirts of the property. After they use a sonic weapon to incapacitate the crowd, Col. Stryker goes through them and picks out exactly who he wants his men to take with them - Mystique, Beast, Peter, and Moira MacTaggert. Jean uses her own psychic powers to hide herself, Scott and Kurt from Stryker's men. Kurt teleports the three of them onto one of the helicopters, which takes them all to Stryker's facility at Alkali Lake. Mystique tries to convince Stryker that Xavier's mind was taken over by a much more dangerous mutant, but the colonel believes they are trying to manipulate him into letting them go. Meanwhile, En Sabah Nur, his Horsemen and Charles are at the outskirts of Cairo. En Sabah Nur forces Charles to telepathically deliver a message to every soul on Earth warning them of their coming doom. Charles also delivers a secret message to Jean instructing her to find him.
Jean, Scott and Kurt try to rescue the others, but the cell Stryker keeps them has an electric current preventing Kurt from teleporting inside. While trying to find the generator that creates that current, the three mutants come across another of Stryker's prisoners. They set the prisoner free, unleashing Weapon X - a brainwashed Wolverine - on the facility to distract Stryker's men. Weapon X instead goes on a rampage, cutting down soldiers left and right, and leaving a trail of corpses in his wake. Weapon X's rampage forces Stryker to flee the facility. When the young mutants come face-to-face with Weapon X again, Jean restores some of his memories to calm him down. As Weapon X escapes into the wilderness surrounding Alkali Lake, Scott hopes they never have to meet him again.
Scott uses his powers to destroy the door to the cell holding their allies. They escape in one of Stryker's military planes left at the facility, and don the experimental flight suits Stryker's men were developing so they can fight En Sabah Nur and his Horsemen. Meanwhile, En Sabah Nur begins the final phase of his plan. He materializes a new helmet for Magneto to shield him from psychic attacks, and then orders him to focus his powers deep in the Earth, manipulating the planet's own magnetic field to extend the reach of his powers across the globe. Magneto's powers wreak havoc in cities across the planet. En Sabah Nur also builds a new pyramid that towers over Cairo in preparation of transferring his conscience into Charles Xavier. The process causes Charles to begin to take on some of En Sabah Nur's features, especially causing his hair to fall out. Once the transference is complete, the ancient mutant plans to use Xavier's psychic powers to enslave everyone left alive after his apocalypse.
Xavier's students arrive in Cairo, and are quickly met by Apocalypse's three remaining Horsemen. Beast fights Psylocke, Scott and Jean battle Storm, and Angel chases Kurt through the pyramid. Mystique and Peter try to convince Magneto to stop this madness by appealing to his sense of family; that she, Xavier, and the others are like a family to him, and that he has more family than he knows. Peter, however, chooses not to tell Magneto that he is his father. Kurt grabs Xavier and brings him back to the plane, which is still flying over Cairo with Moira MacTaggert in the pilot's seat. The other mutants retreat to the plane and begin to escape, but Psylocke and Angel attack the plane. It starts to crash, so Xavier's allies all grab Kurt's tail so he can teleport them all out of there at once. While Psylocke slows her fall, Angel is trapped on the plane when it crashes into the ground. Storm's faith in En Sabah Nur begins to waver when she sees him find his fallen Horseman's lifeless body and calls him "useless."
Transporting so many people simultaneously. The other mutants prepare to make their final stand against En Sabah Nur. Xavier realizes he still has a telepathic link with En Sabah Nur, and psychically battles the ancient mutant in a mental construct of Xavier's mansion. While En Sabah Nur is busy fighting Xavier, Peter gets in a few quick shots at him. En Sabah Nur morphs the ground under Peter's feet to trap him. En Sabah Nur orders Psylocke to finish him, but she turns her blade on En Sabah Nur. The ancient mutant grabs Psylocke by the throat, revealing her to be Mystique in disguise. This convinces Magneto to turn on En Sabah Nur and send an endless stream of rubble at him. Storm and Scott join Magneto in using their powers against the ancient mutant, by En Sabah Nur uses his own psychic abilities to shield himself from their attacks. Jean joins the battle on both the physical and psychic plane, unleashing the full force of her powers to destroy his body. Once the battle with the first mutant is over, Xavier chooses to restore Moira's memories he took away two decades earlier.
Some time later, Jean and Magneto use their powers to rebuild Xavier's school. Charles tries to convince Magneto to stay, but he instead chooses to go back on the run. Mystique and Beast train the new X-Men: Cyclops, Jean, Nightcrawler, Storm, and Quicksilver. They start up a program in the Danger Room involving Sentinels.
At Alkali Lake, men in black suits retrieve what's left of the Weapon X program for the Essex Corporation.
- James McAvoy as Professor X / Charles Xavier
- Michael Fassbender as Magneto / Erik Lehnsherr
- Jennifer Lawrence as Mystique / Raven Darkholme
- Oscar Isaac as Apocalypse / En Sabah Nur
- Berdj Garabedian portays En Sabah Nur in his original form.
- Nicholas Hoult as Beast / Hank McCoy
- Rose Byrne as Moira MacTaggert
- Evan Peters as Quicksilver / Peter Maximoff
- Tye Sheridan as Cyclops / Scott Summers
- Sophie Turner as Jean Grey
- Olivia Munn as Psylocke / Betsy Braddock
- Kodi Smit-McPhee as Nightcrawler / Kurt Wagner
- Alexandra Shipp as Storm / Ororo Munroe
- Lucas Till as Havok / Alex Summers
- Josh Helman as Colonel William Stryker, Jr.
- Ben Hardy as Angel
- Lana Condor as Jubilee
- Željko Ivanek as a Pentagon scientist
- Anthony Konechny as a school jock
Additionally, Warren Scherer, Rochelle Okoye, Monique Ganderton, and Fraser Aitcheson portray Apocalypse's Horsemen. Ally Sheedy makes a cameo as Scott Summer's teacher. "Giant" Gustav Claude Ouimet portrays Blob in the film. Ryan Hollyman and Joanne Boland portray the parents of Scott and Alex Summers. Carolina Bartczak and T.J. MicGibbon portray Magda and Nina Gurzsky, respectively. Sebastian Naskrent and Kamil Orzechowski appear as Milosz and Jakob, respectively. Tómas Lemarquis appears as Caliban. Zerha Leverman reprises her role as Peter Maximoff's mother. Stan Lee and his wife Joanie make cameo appearances as an elderly couple. Hugh Jackman has an uncredited appearance as Weapon X/Logan.
- In the final battle sequence, Psylocke comments to Angel to" split them up". This line was exactly duplicated from the climax battle of 1978 martial arts cult film The Five Deadly Venoms where The Scorpion comments to the Centipede to "split them up" (to defeat the other Venoms)
- Filming began on April 27, 2015 - the same day as the Marvel Studios film Captain America: Civil War. This was announced through a video showing Kodi Smit McPhee teleport as Nightcrawler.
- Similar to X-Men: Days of Future Past, an episode of the original Star Trek series that features a slightly similar plot element is playing in the background of one of the scenes. In this film, it's the episode "Who Mourns for Adonais?", which features a powerful man claiming to be a god.
- "The Four Horsemen" is the name of the song playing in the background of the scene where Apocalypse recruits Angel. It was released on the Metallica album Kill 'Em All in 1983, which is the year the film takes place in.
- The song playing in the background during the Quicksilver speed sequence is "Sweet Dreams (Are Made of This)" by Eurythmics. The single was also released in 1983.
- After watching Return of the Jedi in theaters, Jubilee argues that The Empire Strikes Back is still the best among the three Star Wars films while Scott argues that the first one is still the best. Jean then says at least they can all agree that the third film in a series is always the worst. This is an allusion to the fact that X-Men: The Last Stand, the third film in the first X-Men trilogy, was poorly received by audiences. It's also ironic given that Apocalypse is the third film in this second X-Men trilogy.
- Logan's Weapon X look in the film is strikingly similar to his Weapon X look in the comics.
- Professor X's line, "I feel a great swell of pity for the poor soul who comes to that school looking for trouble," is lifted directly from X-Men. The line is also said to Magneto.
- The movie's ending was originally meant to double as tease of a Gambit film that was in development at the time. The movie's final scene involves Essex Corporation, and Mister Sinister was going to be appear in the Gambit movie.