A brilliant scientist who secretly split the atom in mid 1939, Terry Curtis was kidnapped by the evil Ultra Humanite and forced to participate in Ultra's attempt to blackmail Metropolis. With Terry's aid, these plans were thwarted by Superman and the young scientist returned to his research.
Over the next few years, Terry continued his atomic experiments, taling time out to marry and then sire an infant daughter. In late 1941 one of those experiments went haywire, killing Terry's wife and fatally irradiating Terry and his daughter, Terri.
A few days later, Terry was contacted again by the ultra Humanite, who offered to use his futuristic machinery to save both the Curtises on the condition that Terry would work for him. Seeing no alternatie, Terry agreed to Ultra's terms.
Ultra fulfilled his part of the bargain, using his machines to stabilise the infant Terri's condition, then adjusting those same machines so that they altered the atomic radiation in Terry's body, giving him various atomic powers that he could use to Ultra's benefit. Giving Terry a customised costume and naming him Cyclotron, Ultra sent his reluctant agent out to steal an ancient object called the "Hammer of Thor."
In the course of this robbery, Cyclotron came into conflict with the members of the All - Star Squadron, including his ex-fiancee Danette Reilly, now known as Firebrand. While trying to escape from the All -Stars, Cyclotron accidentally killed a policeman and was wracked with guilt. Later, when the guilt became more than he could bear, Terry grabbed the Ultra Humanite just as that fiend was about to slay the All-Stars and flew high into the stratosphere, where he allowed his atomic energy to detonate, blowing up both himself and Ultra. Terry Curtis died a true hero.