Born in ancient Egypt, the super-villain, Apocalypse (En Sabah Nur), is one of the world's first mutants in the Marvel Universe. Whatever classification system you care to use to describe a mutant's power level (Omega, Class 5, etc.), Apocalypse will always score near the top. Aside from superhuman strength, Apocalypse's powers and abilities are numerous. He is apparently immortal, and he has total control over the molecules of his body, able to alter his form, regenerate from injuries, and adapt to environments. He can absorb and project energy, and he is capable of technopathy, the ability to control technology with his mind directly. But perhaps his most dangerous ability is his genius-level intellect.
Introduced in the pages of X-Factor to be their 'Magneto-level' arch-villain, Apocalypse caused trouble for that team of original X-Men and all the various X-people throughout the late 80's. Since the sudden appearance of such a powerful character can be somewhat paradoxical, a small amount of retroactive continuity (retcon) changes revealed he had been present during several previously published stories. He turned out to be even older still. His real name, En Sabah Nur, was first published in 1993 in CABLE [1993] #6, and his birth time/place was first published in 1994 in X-FORCE [1991] #37. And, finally, the re-weaving of his retcon history was complete when his origin was told in the RISE OF APOCALYPSE [1996] mini-series, linking it to the Fantastic Four's time-travel adventure from FANTASTIC FOUR [1961] #19 published way back in 1963. But nothing cemented Apocalypse into Marvel history more firmly than the AGE OF APOCALYPSE (AoA) crossover event storyline from 1995-96. When Professor Xavier's son, Legion (David Haller), travels back in time to murder Magneto before the man can commit crimes against humanity, Legion inadvertently kills Professor Xavier instead, generating an alternate timeline in which Apocalypse conquers the planet. Alternate versions of all your favorite X-Men fight in resistance to the Apocalypse regime, and the actual X-titles were replaced with AoA versions of the titles throughout the event. The 'Age of Apocalypse' alternate timeline, which was undone at the end of the original crossover event storyline, was later retconned to be an alternate reality, so it could be revisited again...and again.