Tharok continued in his life of crime, though significantly more successful thanks to his robotic components and new-found intelligence. However, he was eventually caught by some officers of the Science Police and was about to head to prison when Cosmic Boy of the Legion Of Super-Heroes arrived with a full pardon if he joined him in defeating a galactic menace known as the Sun-Eater. The Legion of Super-Heroes were forced to find the aid of four other super-criminals with enough power to defeat the Sun-Eater. The five criminals, with Tharok as their leader, became known as the Fatal Five.
The Fatal Five and the Legion of Super-Heroes effectively defeated the Sun-Eater. While they received their pardon for past crimes, the Fatal Five felt that their group was powerful enough to rule the galaxy. Somehow Tharok's robotic mind was able to control the powerful Validus, which cemented his leadership with his fellow criminals. They've fought against the Legion of Super-Heroes several times when they tried to gain control of the universe, and Tharok often found defeat at their hands. Besides being obsessed with ruling the galaxy, Tharok also became obsessed with making the left side of his body more human-like.
Tharok appeared in Justice League: Unlimited as the leader of the Fatal Five and clashed with the Emerald Empress. He fought against the Legionnaires along with Supergirl and Green Arrow.
Legion of Super-Heroes
Tharok appeared in the animated series Legion of the Super-Heroes and instead of leader of the Five he is a member as the Empress is the leader. Tharok clashed with the Legion a few times throughout the series. Tharok was partially responsible for putting Saturn Girl in a coma. Years later, Imperiex freed the prisoners of Takron-Galtos. The Five journeyed back to Earth and helped destroy the Legion. They were all returned to prison except for Validus, who became Imperiex' chief enforcer. Empress was rendered powerless after Matter-Eater Lad ate part of the Eye. They team disbanded as they were absorbed into Imperiex forces.