Cable created Apocalypse
Cable has a connection to En Sabah Nur, a.k.a. Apocalypse, that spans longer than any of the X-Men. In the future, he lived in a world that was in a never-ending war with Apocalypse. Cable would go back and forth through time attempting to find a way to stop Apocalypse from becoming an evil tyrant.
In Cable and Deadpool No. 26 and 27 readers learn something odd- that Cable is, in fact, responsible for making Nur the man we know. Cable’s metal arm (which is infected by the techno-organic virus) gets into En Sabah Nur after he’s shot in the head. Ozymandias brings Nur to a celestial ship where the virus from Cable helped Nur become Apocalypse.
Comic book retcon rating: Weird
This was an odd change. So much so that you don’t hear a lot of comic book fans bring it up. Cable being responsible for Apocalypse added nothing to either of their origins. It was stranger when Cable had a chance to kill him, but left him alive, saying that mutant-kind needed him. You know it’s bad when even Deadpool says something is foolish. It was an interesting story at best and wasn’t anything memorable.