Time Wars 

The X-Men comics of the 80’s and 90’s loved their time travel tales and alternate timelines. Having already explored a nightmarish future where mutants were hunted almost to extinction by giant robot Sentinels in Days of Future Past (which was the basis for the previous X-Men movie), Marvel kicked off a new wave of alternate reality stories featuring Apocalypse. It starts with Cyclops, having no way to help his son in the present, being forced to send Nathan to the far future with the time travelling mutant Askani, in the hope that he could be cured of the techno-organic virus Apocalypse had infected him with.

“Nate” Summers would return from the far future in one form as the mutant Cable; another X-Man innately linked to Apocalypse, who could be gracing our screen sooner rather than later, if the post-credits sting at the end of Deadpool is to be believed.

Apocalypse himself did return thanks to a regeneration chamber during the “X-cecutioners Song” storyline, which featured Stryfe, another version of Cable from the future, attacking the X-Men in the present. Apocalypse was in a much-weakened state when he faced Stryfe, a result of having being woken too early from his regeneration. After being soundly trounced by him, Apocalypse teamed up with the X-Men, even going as far as removing a version of the techno-organic virus from Charles Xavier, who had been infected as a last resort to save him from an assassination attempt.

As he was not much of a team player, Apocalypse once again seemed to meet his end, this time on the moon after fighting his traitorous henchmen who had sided with Stryfe, but he would return again, in another epic time and reality warping story, the Age of Apocalypse.