Mild-mannered composer and pianist from "The Spell of the Hypnotic Chord" story of Ace Magazines comic book The Beyond #30 (January 1955). But when his hands are crushed in an accident, he gets a transplant from executed criminal Zander, a knife-thrower who accidentally killed his assistant. Also, Zander swore revenge. Specifically that his hands would do the revenging. And they do, even though they're connected to a different guy now.
Whilst composing his concerto, a "mystic chord" puts him into a trance, where he murders the people involved in Zander's trial, but with no memory of doing it. When the cops finally catch up, Mark's already dead and his new hands are... gone.