Atmos is a fictional character, a superhero in the future of the DC Comics universe. Atmos was the planetary champion of Xanthu, where the planetary government provided him with a headquarters and training facility.
Fictional character biography
Original continuity
Atmos was the champion of the planet Xanthu. When the villain Universo enacted a plan to conquer his homeworld of Earth, he had several of the United Planets' mindwiped and imprisoned on a distant planet, including Atmos. They were eventually freed, through the efforts of Legion of Super-Heroes members Saturn Girl, Brainiac 5, Chameleon Boy and Dream Girl.
During Atmos' absence from Xanthu, the planetary government ordered Star Boy to resign from the Legion to replace him. Thereafter, Atmos used his powers to enthrall and romance Star Boy's girlfriend Dream Girl. His manipulation was eventually uncovered.
"Five Years Later"
Many years later, Atmos was murdered by B.I.O.N., a Dominator-controlled robotic enforcer developed from the Computo matrix created by Brainiac 5.
Post-Zero Hour
Marak Russen was a child star and famous athlete on his native planet of Xanthu. He was subjected by his planet's government to numerous experiments that turned him into a living nuclear power plant. Now dubbed "Atmos", Russen joined his planet's state-funded team of superheroes, the "Uncanny Amazers of Xanthu", a counterpart to the more well known Legion of Super-Heroes. Together with the Amazers he stood against two invasions of Xanthu: from the alien Blight, and from the minions of the machine intelligence C.O.M.P.U.T.O. from the planet Robotica.
Post-Infinite Crisis
The events of the Infinite Crisis miniseries have apparently restored a close analogue of the Pre-Crisis on Infinite Earths Legion to continuity, as seen in "The Lightning Saga" story arc in Justice League of America and Justice Society of America, and in the "Superman and the Legion of Super-Heroes" story arc in Action Comics. Since Atmos was introduced after the publication of Crisis on Infinite Earths, it is unclear if the character will be reintroduced.
Powers
Atmos has the powers of super-strength, flight, invulnerability and some form of matter manipulation.