Quite a few years back, the maniac known as Joker, was a nervous, unremarkable man living a fairly unremarkable life. After quitting his job as a lab assistant at Ace Chemical Processing Inc. for a failed attempt at being a stand-up comic, he realized he was a failure. With a pregnant wife, Jeannie, living in a tiny apartment in a poverty stricken neighbourhood he began to explore other options. He agreed to help a couple of hoods go through the chemical plant into a neighbouring playing card company.
Shortly before the break in, he learned that Jeannie had died in a freak accident. Forced to go through with the burglary, he also wore a costume identifying him as the Red Hood. The crime was botched by newly installed security measures and the arrival of a certain caped crime fighter. To escape Batman, the young man dived into a chemical waste vat. The chemicals radically changed his appearance, giving him the trademark white skin and green hair. This metamorphisis combined with the senseless death of his wife and his new fugitive status, caused the loss of his grip on reality and the creation of the Joker.
The Joker's real name remains unknown to this day. Even this origin is suspect because the Joker is not only a liar but doesn't really remember his own past, just bits and pieces. We can assertain that he did have a mentally challenged cousin who created the Joker gas and died early in the Joker's career. Besides these few links to another life, the Joker's existence has been defined by the man who made him-Batman.
Jack Napier, a Gotham hood working for a local crime boss, was pulling a job involving the Ace Chemical Processing Plant and the playing card company nest door. Somehow, the job went wrong and Batman inadvertantly caused Jack to fall into a chemical vat.The damage to his appearance drove Jack, an unstable individual to start with, over the edge.