Source: actionagogo.com
4. Angel
AKA Archangel AKA Death AKA Apocalypse AKA Warren Worthington III
Joined: X-Men (1963) # 1
The high-flying Angel is maybe the most changed of the X-Men throughout time. Warren started as the most physically outcast of the team, with his huge wings having to be restrained with harnesses under his clothes. After he left the X-Men, he spent some time with the Defenders and Champions, where he got two incredible costumes. They rule.
When he returned to join the original X-Factor squad, he got his wings impaled and surgically removed. This made him suicidal and he was captured by Apocalypse and given new metal wings, turning him into the Horseman of Death. This would kick off Warren’s Scene period, in which he would rename himself Archangel. And writers would get super indecisive about which version of the character they wanted so he’s pinballed back and forth forever since.

