Apocalypse

Apocalypse, real name En Sabah Nur, is the first mutant. He was a pharaoh of Egypt. He and Nighlock respect each other.

Trivia
 * it is reveal in Weekenders Adventures of Code Red Apocalypse that it was the Dazzlings who had locked him away for ten thousand years.
 * Apocalypse will have his revenge on the Dazzlings in Thomas and Twilight Sparkle's Adventures of X-Men Apocalypse.