Chemo

Chemo is a gigantic monster entirely composed of toxic chemicals and radioactive waste. It has shown very little signs of intelligence, but is clearly sentient and takes pleasure in the destruction it causes. Originally an enemy of the Metal Men, although the level of danger makes it threatening to everyone. It has been a member of several villainous teams including the Secret Society of Super-Villains, Brotherhood of Evil, Suicide Squad and the Injustice League.

Chemo was created by Robert Kanigher and Ross Andru, first appearing in Showcase #39 (1962).