Real Name: Marak Russen
Super-Power(s): Flight, super-strength, super-invulnerability, nuclear bolts, some form of matter manipulation; secretly, will subversion
Planet of Origin: Xanthu
Planet of Origin: Xanthu
Legion Seniority: Atmos was the fourth recruit to join the Legion in the mostly-unchronicled era known as the Five-Year Gap.
Atmos was the champion of the planet Xanthu, created at the behest of the planet's ruling Tribune by geneticists. And so former child actor and amateur athlete Marak Russen, was chosen as the subject for an experiment to recreate the comet radiation that gave Thom Kallor (Star Boy) his temporary Kryptonian-like powers. He became planetary protector, with all the privileges entailed, and then... he disappeared without a trace. He had been mindwiped and imprisoned by Universo as part of a plot to conquer Earth. This is where he met and fell in love with Dream Girl. After the Legion rescued the taken heroes, he tried to join, but was rejected for his imperious attitude. He began a relationship with Dream Girl and returned with her to Xanthu, sparking a competition with Star Boy for the hearts of both their people and Nura Nal, which it turns out he had enthralled with his powers.
After the Magic Wars, Atmos reapplied and was accepted to the Legion after Earth had been infiltrated by the Dominion. He stayed only a short while before growing uncomfortable with Earthgov's anti-Legion stance, then resigned. But he was captured by the Dominators and eventually used him to test their artificial super-being BION's capabilities. BION killed him, though the Dominators released a fictional story about his death at Khundish hands.
After the Reboot, Atmos had the same basic origin story, but joined his planet's state-funded team of superheroes, the "Uncanny Amazers of Xanthu". As a member of the Amazers, he stood against two invasions of Xanthu, one from the alien Blight, the other from Robotica's C.O.M.P.U.T.O.
After the Threeboot, Atmos does not seem to exist.
After Infinite Crisis, presumably Atmos' history has been restored, though he has yet to reappear (aside from a cameo in Final Crisis: Legion of 3 Worlds, which could happen anywhere on his time line).
Important Atmos Stories:
Xanthu's protector, Atmos, mysteriously disappears in this,
his first appearance (note that the Who's Who entry is in error)
Atmos is one of many heroes abducted by Universo; he meets Dream Girl in the internment camp
Atmos applies for the Legion and starts romancing Dream Girl
Atmos completes his seduction of Dream Girl and brings her to Xanthu
The post-Gap fate of Atmos is revealed
The Reboot Atmos is one of the heroes of Xanthu considered for Legion membership