Captain Atom
When Captain Atom first came out in the 1960s, (drawn by Spider-Man co-creator Steve Ditko no less), it seemed that radiation and nuclear power was the magic potion that could turn people into heroes and monsters. The nuclear boogeyman isn’t gone, and thanks to the recent disaster at the power plant in Fukushima, nuclear disaster is more omnipresent in our collective minds, so maybe the time is right for a captain of the atom. A man burned by the system, but given a second chance at life and reborn as a hero to become a frequent fixture of the Justice League across almost all its various incarnations.
As the story goes, an Air Force Officer named Nathaniel Adams, convicted of a war crime he didn’t commit, finds his death sentence commuted in exchange for his participation in a military experiment. He’s secured inside an alien spaceship, which is placed over an atomic bomb and detonated. The resulting explosion welded the alien metal to his body and sent him 25 years into the future, arriving in the present day with the powers of strength, flight, energy blasts and the ability to absorb atomic energy. Because of his dual dedication to the air force and being a superhero, Captain Atom sometimes finds himself torn between his duty to the chain of command and the fact that the chain is sometime corrupted by a few bad links.
In Man of Steel, it’s implied that there’s a healthy distrust of Superman on the part of the government and the military, which could jive nicely with the comic book background of Captain Atom. Maybe they sneak him on to the newly formed Justice League with the intention of keeping eyes on the highly suspicious working relationship between Superman, Batman and Wonder Woman. Maybe Captain Atom is a good soldier, and doesn’t understand the intentions of his superior officers. And maybe he then realizes his boss’ ill-intentions and dedicates himself to being the superhero he’s meant to be.