Captain Atom, the Original Atoman

Origin

Exposed to an atomic explosion twin brothers are somehow fused into one person, thinking he has lost his brother the seeming remaining brother studies to become a nuclear physicists, however Dr. Bikini Rador later finds that his brother is not dead but is a part him and that when he shouts the phrase “Exenor!” he switches places with his brother who calls himself Captain Atom, the Original Atoman.

The otherwise unnamed brother known as Captain Atom is super strong, can fly, hear radio waves, exhale blasts of heated air from his lungs and is nigh-invulnerable.

Deciding to fight crime Bikini Rador takes on a second identity as Agent Larry Lockhart of the FBI, and then things become more than a normal man can handle he switches with his super-powered brother.