Chemo

Chemo is the popular Metal Men foe!
Pre-Infinite Crisis
A scientist named Ramesy Norton used Chemo to store his failed chemical experiments. After filling it will various dangerous chemicals, he made an unsuccessful growth chemical. He poured it into Chemo (Big Mistake!), causing him to grow to roughly 25-feet and gain sentience. Chemo learned how to expel the hazard chemicals in his "body". He poisoned / killed Norton and went on a rampage. But, the Metal Men stopped him. Chemo returned various times, despite the Metal Men seemly "killing" him after each encounter and his limited intelligence. Brainiac and Lex Luthor got Chemo to cause mass destruction on Earth-4. But, the Negative Woman used to her energy powers to shatter Chemo's shell. After the Crisis on Infinite Earths, Chemo was brought back to "life" and attack many heroes and joined Lex Luthor's Suicide Squad.
Infinite Crisis
The Society (Secret Society of Super Villains) had Chemo terrorized Blüdhaven, until Superman threw him into space.
One Year Later
In Outsiders- Five of a Kind, Dick Grayson found Chemo floating in space. The cover Justice League of America (vol. 2) issue 13 reveals Chemo joined the Injustice League.
Salvation Run
Chemo is seen being sent to a prison planet. Joker and Gorilla Grodd used Chemo to destory a burrowing creature that were attacking the super villains.
References:
http://en.wikipedia.org/wiki/Chemo_(comics)
http://www.rci.rutgers.edu/~cje/mh/ME/ChemoCJE.gif