Captain Atom Reading Order (Nathaniel Adam)
Created by Joe Gill and Steve Ditko in 1960, Captain Atom first appeared in Space Adventures #33 published by Charlton Comics, a publishing company later acquired by DC Comics. Back then, the character was named Allen Adam, a technician who was trapped in a rocket that exploded. He should have died but instead became a superpowered atomic hero. His series continued for a few years (until December 1967). Back then, he had a red and yellow outfit and pretty generic powers.
In 1983, DC Comics acquired Charlton Comics’ action heroes and asked Alan Moore to do something with them. That’s how Captain Atom became Doctor Manhattan in Watchmen. Moore’s take on the characters was not what DC’s editors had in mind for them and the British writer had to rewrite some of them to create his own version while the publisher introduced Charlton’s super-heroes (like Blue Beetle) in its Post-Crisis universe. During the Crisis on Infinite Earths, it was established that they were on Earth-4. After that, they found their way into the main continuity.
Captain Atom was then reinvented as Nathaniel Christopher Adam, a United States Air Force officer and Vietnam War veteran. Framed and condemned for a crime he didn’t commit, his only option to survive was to join the military experiment called ‘Project: Captain Atom‘ during which he was placed in an alien craft positioned next to an atomic bomb. The goal was to test the resistance of the ship, but the result was ultimately the creation of a superhero. During the explosion, Nathaniel was disintegrated, but he mysteriously reappeared 18 years later, now bonded with the alien metal that has the ability to tap into the “Quantum Field”. Captain Atom can absorb energy to a certain point (beyond that, he jumps in time).
In 1986, as Captain Atom just reappeared, the military forced him to work for them. He eventually joined the Justice League and later became the leader of Justice League Europe. Through the years, he joined other teams, fought his enemy through times, and became a villain before returning to normal.