The cyborg leader of the Fatal Five.
A petty thief from the planet Zaron, Tharok was partially destroyed while trying to steal a nuclear device. Rescued by the authorities, his missing body sections are replaced with robotic parts. Unfortunately, the addition of a robot brain gives Tharok a super-intelligence which he uses to plan crimes and seek revenge on the lawmen he blames for his condition.
Superboy and the Legion of Super-Heroes first encounter Tharok when they enlist him in their struggle against the Sun-Eater. While he initially seems disposed to help them, Tharok soon betrays the Legion and forms the criminal group known as the Fatal Five to battle Superboy and the Legion (Adv No.352-353, Jan-Feb 1967: "The Fatal Five, Parts I-III: To Save a Galaxy; An S.O.S. to Evil; and Slain by the Sun-Eater").