Chemo is a giant Super-villain in DC Comics. He first appeared in Showcase #39 in July 1962. He can fire hazardous chemicals and regenerate from attacks. Although he is the nemesis of the Metal Men, I consider him to also be an adversary to Superman. He has fought Superman on many occasions and even some other heroes. Chemo has been affiliated with the Injustice League, the Suicide Squad, and the Secret Society of Super-villains. He was also part of the group of villains that teamed up during the Crisis on Infinite Earths Series.
Origin: There was a scientist named Ramsey Norton that would always place chemicals from his failed experiments in a plastic container shaped like a human. When he places a failed growth serum into the container it comes to life. Chemo, the plastic container, kills Norton and rampages in the city until he is eventually stopped by the Metal Men.