VIDEO : Nathan Fillion is Becoming a Super Hero

Fan favorite Firefly star Nathan Fillion is Simon Williams, a.k.a. Wonder Man in Guardians of the Galaxy Vol. 2.. In the Marvel Comics Universe, Simon Williams is a former member of the Masters of Evil, and brother of villain the Grim Reaper, who reformed and joined the Avengers. He was later dragged back into the Avengers? active roster, despite becoming a pacifist, as a member of the Avengers Unity Division.