this

He's an X-men bad guy.

Apocalypse was born in Egypt thousands of years ago and at the time seemed to just be a really smart, grey skinned, tough guy who didn't age and freaked people out. But then he found a bunch of alien technology (that stuff is always laying around ancient Egypt isn't it?) that he used to give himself super powers. Specifically any and every superpower the writers think is cool at the time. He takes long naps and every few centuries he wakes up, tries to figure out who is the fittest among humanity by handing out death, destruction and new technology, then goes back to sleep for a few centuries to give his efforts time to pay off.

In the event of Apocalypse's demise, his Death Horseman is transformed into the Heir of Apocalypse. There's always going to be someone to carry on his will - he does what the Celestials want him to do, and they don't intend for humanity to be the final stage of evolution, so humanity's gotta go.

Y'know, we don't have to fight...