Johnny Rocco (Edward G. Robinson) - evil bastard
I think Edward G. Robinson really stole the show here. His convincing portrayal of Johnny Rocco was such a stark portrait of evil, that I'm hard pressed to recall a more chillingly evil person in movie history.
"The sword is the soul. Study the soul to know the sword. Evil mind makes an evil sword." — Toranosuke Shimada, “The Sword of Doom“