En Sabah Nur, also known as Apocalypse, is the main antagonist of X-Men: Apocalypse. Supposedly the first mutant to ever walk the Earth, he was born before recorded time and lived for thousands of years. Possessing awesome powers far greater than any mutant of the modern age, civilisations rose and fell in accordance to his will. In 3600 BCE, he ruled over ancient Egypt and was worshipped as a god. However, his reign ended when he was betrayed by his closest guardsmen who gave their lives to seal him away beneath the Earth. In 1983, cultists devoted to Apocalypse would find him buried beneath Cairo and awaken him, allowing him to emerge so that he could cleanse the world of those he deemed too weak to be worthy of life.
This incarnation of Apocalypse was portrayed by Oscar Isaacs.
Apocalypse was the first mutant to be born upon the Earth and possessed tremendous strength and power. He would prolong his life over thousands of years by transferring his essence into other mutant bodies, thereby gaining their powers as his own. By 3600 BCE, he had accumulated many abilities: teleportation, energy manipulation, telekinesis, molecular manipulation, power enhancement and regenerative healing. He also wore a suit of armour that increased his already considerable endurance.
In 3600 BCE, Apocalypse was undergoing a ritual to transplant his consciousness into a new body as his current one was succumbing to age. At this time, dissidents within his ranks attempted to interrupt the ritual, seeing it as the only opportunity to kill him and end his tyranny. Though the traitors were all killed, they succeeded in destroying Apocalypse's pyramid, burying him and his Four Horsemen. While the Horsemen perished, one of them cast a shield over Apocalypse's new body, protecting and sealing it so that he could awaken at some point in the future.
In 1983 AD, a group of cultists who worshipped Apocalypse discovered his tomb in the catacombs beneath Cairo. The tomb was also discovered by CIA agent Moira MacTaggert who watched from a distance as the cultists enacted their ritual to awaken the slumbering tyrant. Apocalypse awoke and emerged, exploring the streets of Cairo. He encountered a young street thief, Ororo Munroe, and after killing a group of men who attacked her, followed her back to her home. There, Apocalypse touched Ororo's TV set, reading the electronic signals being broadcast through it. This allowed him to learn about the state of the world and he was disgusted by what he found: a world governed by weaklings. Deciding to remake the world in his image, Apocalypse convinces Ororo to help him and appoints her as his new Horseman of Famine.
Apocalypse then travels the world in search of powerful mutants to recruit as his Horsemen. First he travels to the Iron Curtain and recruits the telekinetic warrior Psylocke, appointing her as his Horseman of Pestilence. Next, he recruits Warren Worthington III in Berlin who becomes the Horseman of Death. Finally, Apocalypse travels to Poland where he finds the former mutant terrorist Magneto, convincing him to join him as the Horseman of War.
With his new band of Horsemen, Apocalypse invades the Xavier Institute and abducts Charles Xavier. Tapping into Xavier's mind, Apocalypse uses the professor's immense psychic powers to seize control of several military officials around the world, gaining access to every nuclear weapon on the planet. Apocalypse's plan is not to start a nuclear war, however, but to end all such conflicts by launching all of the missiles into space.
With the world's military powers in disarray, Apocalypse constructs a giant pyramid in the centre of Cairo. He then amplifies Magneto's power and encourages him to use his powers to manipulate the Earth's magnetic poles, tearing up every magnetic component from around the world and causing massive death and destruction worldwide. He then takes the captive Xavier into the pyramid where he intends to transfer his essence into the professor's body. By doing this, Apocalypse will gain Xavier's psychic power and will be capable of dominating every mind on the planet.
Under Mystique's leadership, the X-Men arrive in Cairo to do battle with Apocalypse's Horsemen. During the battle, Mystique manages to convince Magneto to turn away from Apocalypse and help them while Jean Grey reaches out to Professor X telepathically, urging him to resist Apocalypse's attempts to possess him. Nightcrawler manages to rescue Xavier from the pyramid before Apocalypse can occupy his body, but the villain emerges from the pyramid and joins the battle himself. After witnessing Archangel's death, Apocalypse is disgusted by his Horseman's "uselessness". Storm witnesses this callous behaviour and realises that Apocalypse doesn't care about her or the others, seeing them only as expendable pawns. She decides to betray him and join the X-Men in stopping him.
In the final confrontation, the X-Men all unleash their full power on Apocalypse while Charles battles the tyrant on the astral plane. Apocalypse is able to shield himself from the heroes' onslaught and appears to be winning his psychic battle with Xavier until Jean Grey taps into the Phoenix Force, unleashing her true power. Jean and Magneto use their combined power to rip Apocalypse's armour off of him, leaving him vulnerable. After he has been overwhelmed by a constant barrage of optic blasts, telekinesis, lightning and been speared by multiple scraps of metal, Jean then uses the full power of the Phoenix to disintegrate Apocalypse's body, destroying him once and for all.