Weight: 225 lbs
Tharok was a criminal on his native planet of Zadron. During one of his crime activities, he tried to steal a nuclear device that detonated when he was caught by an officer of the Science Police. Unfortunately for Tharok, that officer shot a blast which caused the detonation and it destroyed the complete left side of his body. Miraculously, Tharok remained alive and he was rushed to the nearest medical center. The doctors and scientists there quickly replaced his missing left side with a robotic component. The procedure was rushed because they feared they would lose Tharok's life. When Tharok revived, he found himself significantly smarter, thanks to his half-robotic brain. Unfortunately, the life-saving procedure also caused Tharok to look like a monster and his appearance gave him nothing but anguish.
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.
Without Tharok's acknowledgment, a scientist that helped implant Tharok's robotic half stole a sample of Tharok's brain. He used the brain for cloning issues and the brain grew too powerful, gaining strong telepathic abilities. The brain continued to grow and formed a full man identical to a human Tharok. However, this cloned version of Tharok had to absorb the life force of others to survive. Through unexplained means, this clone, known as Dark Man, was able to telepathically control others, specifically his progenitor, Tharok. Dark Man was responsible for the creation of the League of Super-Assassins, giving them their super-powers so they could defeat the Legion of Super-Heroes. After the League of Super-Assassins failed in destroying the Legionnaires, Dark Man used his powerful telepathic abilities to force Tharok to lead the Fatal Five into destroying the Legion of Super-Heroes. A kidnapped Saturn Girl was able to block Dark Man's telepathic control of Tharok and that caused Tharok and Dark Man to rush into battle. When they made contact, an explosion occurred and neither was seen again.
Tharok's robotic side had given him vast intellect and super-strength. Tharok had a certain degree of skill in unarmed combat. He had been shown to have created gadgets to use as offensive weapons, including energy blasts and 'stun bubbles', balls of energy that stunned whomever touched it. Tharok's strongest asset is his intellect, which has got him out of many sticky situations.
The clone of Tharok had the ability to siphon the life force of others so he could survive. He also had a vast intellect and powerful telepathic powers which he used to control others.
In other media
He appears in JLU battling the Legion, Green Arrow, and Supergirl.
He also appears in the Legion of Superheroes animated series.