Chemistro is a member of the Masters of Evil.
During the Vault breakout, Chemistro tried to recover his equipment, but was punched in the face by Hawkeye, another prisoner.
When the Masters of Evil stole and guarded the Norn Stones, Chemistro was one of their new recruits and faced Hawkeye, now a member of the Avengers. Chemistro wanted revenge on Hawkeye, who annoyed him by not remembering him and confusing him with other villains like Paste Pot Pete.
When Enchantress decided to dispose of the Masters of Evil, she turned Chemistro into gold with his own gun. He seemingly is still alive.