Though many have been related, a definitive history of the Joker before the chemical bath has never been established in the comics, and his real name has never been confirmed. He has been portrayed as lying so often about his former life that he himself is confused as to what actually happened. As he says in The Killing Joke: "Sometimes I remember it one way, sometimes another... if I'm going to have a past, I prefer it to be multiple choice!" In Arkham Asylum: A Serious House On A Serious Earth written by Grant Morrison, it is said that the Joker may not be insane, but have some sort of super-sanity, where he creates himself each day to cope with the chaotic flow of modern urban life.
The first origin account, Detective Comics #168 (February 1951), revealed that the Joker had once been a criminal known as the Red Hood. In the story, a scientist looking to steal from the company that employs him adopts the persona of Red Hood. After committing the theft, Red Hood is dropped into a vat of chemical waste by Batman. He emerges with bleached white skin, red lips, green hair, and a bizarre permanent grin.
The most widely cited backstory can be seen in The Killing Joke. It depicts him as originally being an engineer at a chemical plant who quits his job to become a stand-up comedian, only to fail miserably. Desperate to support his pregnant wife, the man agrees to help two criminals break into the plant where he was formerly employed. In this version of the story, the Red Hood persona is given to the inside man of every job (thus it is never the same man twice); this makes the man appear to be the ringleader, allowing the two criminals to escape. During the planning, police contact him and inform him that his wife has died in a household accident.