Dr. Charles Langley is the man responsible for creating Mr. Atom. Langley believed he could create artificial life through atomic energy. Langley built a gigantic robot body that he intended to bring to life through a gradual process. However, his calculations were wrong and the robot suddenly came to life through an explosion that not only gave Mr. Atom fantastic powers, but programmed him with great knowledge.
Leaving Langley among the debris of his wrecked laboratory, the atomic robot went forth into the world of men. Seeing how much mightier he was than they, he determined to become Earth's ruler. The people could serve him or perish - it made no difference to him, because he was untinged with human feeling. He would kill without mercy or remorse.
Meanwhile, Captain Marvel saved Langley, and the scientist told him of his robot, so he was forewarned when he went to battle a creature at the UN who was demanding the allegiance of the Earth - and who had already killed one delegate with a blast of atomic power. Through two encounters, the pair fought one another to a draw. Then they each struck one last mighty blow - and Captain Marvel won. Mr. Atom was contained in a thick - walled lead underground prison from which he could not escape - yet Cap himself could not destroy him.
Sometime later, beings from a giant comet freed Mr. Atom and teamed up with him to subjugate Earth - though they planned to destroy him once it was done. To demonstrate his power, Mr. Atom began destroying a town - but was stopped by Captain Marvel. He and the Comet men headed for the comet by spaceship, only to see it blow up. Mr. Atom insisted the beings help him conquer Earth anyway, and this led to an almighty battle in which it appeared they were all destroyed.
However, Mr. Atom had not been killed, but hurled 100 years into the future, to a world where almost everything was run by atomic power. This seemed a perfect world for him to rule. But Captain Marvel, warned by the spirit of Shazam traveled to the year 2053 to foil the robot's plans. This time, Mr. Atom was apparently destroyed by a burst of atomic energy.
In fact, when King Kull the Beastman took over the Rock of Eternity, he used his genius to bring Mr. Atom from the 21st Century to aid him. A battle with the heroes of three Earths - including the Justice League and Justice Society ended with Atom being propelled to a distant star.
Mr. Mind's machinations returned him to Earth, and this time Captain Marvel sent him into orbit around the sun. But the magic of Oggar again brought him back - this time to join the Monster Society of evil. Ultimately, Captain Marvel tossed Mr. Atom from the Rock of Eternity to another galaxy, one in which life never developed, where he could do no harm.
He later joins The Secret Society of Supervillains and is apparently destroyed by Kal-L, the Golden Age Superman. He is not destroyed and is one of the villains helping Prometheus plant explosive devices around U.S. cities and eventually attempt to flee once the devices have been planted. The Justice League attack Mister Atom before crossing the border and he is defeated and captured by Starman and Congorilla.