In 1968, Air Force Captain Nathaniel Adam was falsely accused and court-martialed for murder and treason. In order to get a Presidential pardon for his crimes, Adam was forced to participate in an atomic experiment using a shield created from an indestructable alien alloy. The experiment failed and Adam was catapulted through the quantum field and 18 years into the future -- without aging him a day. His body melded with the alien alloy and acted as a conduit into the quantum field, giving him amazing powers. His original pardon null and void due to his "death," Adam consented to work for the U.S. government as a super-hero -- codenamed Captain Atom -- to earn a new one. Eventually clearing himself of the false charges against him, Captain Atom went on to join the Justice League, and has served as the leader of the European branch of Justice League International and also led the satellite team known as Extreme Justice.

By coating himself at will with the alien alloy that is now part of his body, Captain Atom gains the powers of invulnerability, super-strength, anti-gravity powers and the ability to fire atomic energy blasts. Also able to absorb most kinds of energy, he runs the risk of "quantum jumping" through the time stream if he absorbs too much.