Cyborg Superman

Cyborg Superman is the product of a scientific exploration gone totally wrong. Incapable of feeling pain or allegedly of even dying, he strives for the destruction of Superman and his Justice League allies.

History
Cyborg Superman first appeared posing as the real Superman following the latter's apparent death. He designed a plan that would drastically alter the ranks of the Justice League. Using a team of villains composed of Clayface, Mr. Freeze, Copperhead, the original Parasite, and others, he orchestrated an attack which resulted in the apparent deaths of Captain Marvel, Atom Smasher, and Firestorm. This was a heavy loss for the team, and Cyborg Superman took advantage of the mood to make the League more ruthless, often resorting to severe beatings and even killing some criminals. After falling into disagreement with the Flash, he captured him in the Phantom Zone.

Several members of the League began to grow suspicious of Cyborg Superman, ultimately leading to their discovery that the real Superman was in a comatose state in his Fortress of Solitude. The League was able to defeat Cyborg Superman with the help of the returning Captain Marvel and the reawakened Superman.

Cyborg Superman would not appear again until much later in the Justice League's career, now the ruler of a planet made entirely out of technology. The League was able to defeat him by thrusting him into a black hole, thanks mainly to the efforts of Firestorm and Green Lantern.