John Corben, or also better known as Metallo, is a recurring antagonist in the DC Animated Universe, appearing as a major antagonist in Superman: The Animated Series and a minor antagonist in both Justice League and Justice League Unlimited.
He was an infamous mercenary and hit man who would later become the cyborg Metallo after he was unknowingly infected with a rare disease by Lex Luthor's scientists. Metallo then becomes one of Superman's deadliest foes as well as for the Justice League, joining Gorilla Grodd's Legion of Doom.
He was voiced by Malcolm McDowell, who also played Lord Maliss, Alex, Caligula, Colonel F. E. Cochrane, Tolian Soran, Kesslee, Sinclair and Geoffrey Tolwyn.