The year 2000 comic book arc "Apocalypse: The Twelve" told the story of twelve beings who were said to be able to defeat Apocalypse once and for all (which turned out to be a ruse, as Apocalypse orchestrated the idea himself so he could use the twelve to become more powerful than the Celestials themselves). During the arc, Apocalypse attempted to use Nate Grey as a host body for him to move his energy and consciousness into, essentially merging with him. Cyclops pushed Grey out of the way, however, and ended up being merged with Apocalypse himself. The resulting being was a cross between the two - essentially a monstrous Cyclops with Apocalypse's technological augmentation attached to him, giving him the amalgamated powers of both characters - and was eventually separated when Jean Grey telephathically tore Apocalypse's essence out of the merged being.
