Plastic Man had been a crook named Patrick "Eel" O'Brian when he was shot by a security guard and struck by a falling drum full of an unidentified acid, some of which entered Eel's wound. He was saved by a mysterious order of monks whose example cured his penchant for crime. The acid bath gave him the ability to change his shape. He wore dark glasses and a red-and-yellow costume as flexible as his body. Whatever shape he took, the colors remained the same, so there might be a red-and-yellow chandelier over a table full of plotting gangsters, or a red-and-yellow abstract painting hanging on the wall, but the villains never caught on until it was too late.

Plastic Man soon acquired sidekick Woozy Winks, a doofus who was originally magically enchanted so that nature itself would protect him from harm. That eventually was forgotten and Woozy became simply a dumb but loyal friend of Plastic Man.

Plastic Man was asked to join the Justice League of America because they felt that he was more versatile than Elongated Man. Plastic Man thought of the plan to defeat Queen Bee since he knew that bees are blind to red. In "The Obsidian Age" Plastic Man was torn apart and left at the bottom of the see for 300 years. Thanks to Batman, Plastic Man regained his shape and mind. Later, Batman helps Plastic Man get in touch with his son who has the same powers as his father. Plastic Man decided to take leave from the League to get in touch with his son. When Martian Manhunter turned into Fernus Plastic Man was the only one able to stop him, but Eel forgot all about his alter ego as Plastic Man. Eventually he remembered and defeated Fernus.