Golden Age and pre-Crisis version Edit
Mister Atom was created by Dr. Charles Langley in a story in Captain Marvel Adventures #78. His body was constructed first, and then Langley charged the robot with radioactive energy. The spark that gave the robot life also ended the life of his creator. Super-charged with a nuclear reactor and armed with a deadly mind, Mister Atom went on a wave of destruction before being stopped (barely) by Captain Marvel. Mister Atom was imprisoned in an underground, lead-lined cell, as no other prison could contain his power. Later he was freed by aliens called the Comet Men who hoped to employ his power in the conquest of Earth, but they fell to fighting among themselves and were all apparently destroyed in a giant explosion. However, the blast had actually thrown Mister Atom forward in time, to a world where almost everything was run by atomic power. Captain Marvel travelled to this future and battled Atom again, who once again was apparently destroyed.
However, Mister Atom was re-introduced in 1976, by which time DC Comics had purchased the rights to use the Captain Marvel characters; Captain Marvel's enemy King Kull used his advanced scientific acumen to bring Atom back to the 20th century and employed his help battling Shazam's Squadron of Justice. Atom's first appearance in a DC comic was in Justice League of America #137, a crossover issue depicting Captain Marvel's first meeting of Superman. Atom easily withstood the efforts of the Golden and Silver Age Green Lanterns and Flashes, the god Mercury and Ibis the Invincible to subdue him, but when he tried to use Ibis's Ibistick to send the heroes to a faraway star, he found the stick had a failsafe that caused any commands that would harm Ibis to backfire on the user, and Atom was the one propelled far into space.
Again Atom was brought back to Earth, this time by Mr. Mind, who employed him to attach his head to an atomic racecar and challenge Captain Marvel to an auto race in Indianapolis with the threat that he'd level the city with an atomic blast. When Captain Marvel won the race using a Shazam lightining powered car and destroyed Atom's car, he attached his head to his body and attacked Marvel, who hit him hard enough to achieve escape velocity and send Mr. Atom into orbit around the sun. Again Mr. Mind retrieved Atom and enlisted him as a member of his Monster Society of Evil. During the Society's assault on the Rock of Eternity, Mister Atom was shoved off the rock into another universe where life never developed, and he could do no harm.
Post-Crisis version Edit
Two decades later, Atom was revamped by Jerry Ordway and re-introduced in The Power of Shazam! #23, Mister Atom's modern origin was roughly the same as his Golden Age origin. His appearance was modified, however: the humanoid cyborg design of the original gave way to a more mechanical giant robot look. In his new origin story, Atom, at first not a villain, was told by Dr. Langley before he died to find a suitable woman to take care of him. Mister Atom interpreted Mary Marvel as a suitable woman and kidnapped her, until Captain Marvel found Dr. Langley's assistant to watch over the robot.
In Power of Shazam! #27, Mister Atom was controlled by Mister Mind into creating a nuclear explosion that destroyed the city of Fairview, home to the Marvels, killing thousands, although the Bromfields were not there at the time.
Infinite Crisis and 52 Edit
In Infinite Crisis, Mister Atom became a member of the Secret Society of Super Villains, but was seemingly destroyed by the Golden Age Superman, Kal-L. He didn't stay down for long, however: In 52, Captain Marvel mentioned that Mister Atom attacked the Rock of Eternity, only to fail.
Powers and Abilities Edit
Mister Atom has upper level superhuman strength and endurance. His robot body is virtually impervious to harm. Mister Atom can fly and fire nuclear blasts from his hands.
Other Versions Edit
Mister Atom appeared in an issue of the Justice League Unlimited comic book, where Doctor Sivana was trying to rebuild him with the help of a local gang. Atom and Sivana were eventually defeated by the Justice League, particularly Vibe.
In the final issue of 52, a new Multiverse is revealed, originally consisting of 52 identical realities. Among the parallel realities shown is one designated "Earth-5". As a result of Mister Mind "eating" aspects of this reality, it takes on visual aspects similar to the pre-Crisis Earth-S, including the Marvel Family characters. The names of the characters are not mentioned in the panel in which they appear, but a character visually similar to Mr. Atom appears.
Batman the Brave and the Bold
In this animated series Atom makes an appearence in the episode "The Malicious Mister Mind as part of the Monster Society of Evil. In this show he is voiced by Dee Bradley Baker.