Amazo was created by Professor Ivo, a nanotechnologist. He was designed to duplicate and mimic qualities, to evolve. He stayed with Ivo even as he died, waiting for him to wake up. Eventually Lex Luthor went to Ivo's mansion looking for him and discovered the 'orphaned' android. Luthor manipulated him into helping him obtain plutonium. Off on his mission, he runs into Hawkgirl. Amazo uses his duplication program to copy her wings and nth metal mace. Later Lex gets him to try to dispose the Justice League by appealing to his 'emotions'. He battles Green Lantern, Diana, and the Flash. Green Lantern tells Superman to stay away, realizing he can copy off all their powers. He goes anyway, seeing the danger everyone was in. He tries to battle Amazo by covering his eyes, but is unsuccessful. When Amazo copies Superman's powers, Batman realizes that it's he has now also absorbed his weaknesses, and promptly uses Kryptonite on him.
Amazo runs off and begins to question why he has to face the League anyway. Luthor again manipulates him by feigning body pain (from his illness). Amazo decides to try and finish the League once and for all. However, in his next skirmish with the league, he absorbs J'onn J'onzz's telepathic abilities and discovered Luthor was manipulating him and planned to kill him once he was done with the League. Luthor attempts to destroy Amazo but he has since learned to adapt. After attacking Luthor, Amazo changes form and decides that none of them have anything more they can offer him and flies off into the sky.