During the 1960's, the American government began a program of research, exposing test subjects to radiation. All died, except one - Arthur Thompson, who gained atomic powers. He entered the public eye in 1962, when he intervened in the Cuban Missile Crisis, saving untold millions of lives.
He became famous as the world's first superhero, but he was never close to the public eye. However, he refused to get involve in world affairs, especially during the Czech war. The following year, he moved his family to the Moon before retiring from heroics for good.
Thompson's current status is unknown. It is not inconceivable that he is still alive, but the effect of his powers on his system is unmeasurable. What is known is that he had at least two children, which one of them carried on as Arthur's successor to bearing the mantle of the Atom. Arthur's grandson, Adam, became the third incarnation of the Atom following the death of Arthur's son at the hands of the Fatal Five.
- As of Tangent: Superman's Reign, there hasn't been any mention of Arthur Thompson's responsibility for the cause of the failed Cuban Missile Crisis that is seen in the Tangent Comics, and is unknown whether the events depicted are transfer over to the recreated 52 Multiverse. Although it is possible that all traces of Arthur's history is still covered up by the time of the Superman's rule.
- Arthur Thompson's origins in radiation experiments on human beings committed by the U.S. military is based on what actually occurred in the 1950's, such as the Desert Rock exercises.
- Arthur Thompson's early costume was conceived on with a "committee mentality" and parts of the costume are a stylized version of an astronaut's suit while limited by the technology of contemporary time.
- 8 Appearances of Arthur Thompson (Earth-9)
- 2 Images featuring Arthur Thompson (Earth-9)
- Quotations by or about Arthur Thompson (Earth-9)
- Character Gallery: Arthur Thompson (Earth-9)
Tangent Comics Character