Cosmic King was a native of Venus in the latter half of the 30th Century. He was experimenting in transmutation when an accidental exposure to a ray in his laboratory gave him the power to transmute inanimate objects. Exiled in disgrace from Venus because the natives felt transmutation was inherently evil, he took the name Cosmic King and began a criminal career.
Cosmic King has served as a member of the Legion of Super-Villains and has battled the Legion of Super-Heroes multiple times.
Of the three founders of the LSV, Lightning Lord, Saturn Queen, and Cosmic King, Cosmic King is the only one who does not have a similar home planet or powers of his good opposite, Cosmic Boy
Most recently, he attacked the Legion Academy and appeared to die in battle with Variable Lad, though his death has not been confirmed.