In Tim Burton’s 1989 film Batman, what is the Joker’s birth name?

The Joker’s birth name is Jack Napier in Tim Burton’s 1989 film Batman.

Jack Napier is introduced as a criminal working for Gotham City mob boss Carl Grissom. During a confrontation at the Axis Chemicals plant, Batman causes Napier to fall into a vat of chemicals. Napier survives with severe physical changes and adopts the identity of the Joker.

This origin differs from the comics, where the Joker’s pre-transformation identity is commonly unknown or deliberately uncertain. The film’s version gives him a direct personal connection to Bruce Wayne by making Napier responsible for the murder of Bruce’s parents before he becomes the Joker.

Jack Nicholson played the Joker, while Michael Keaton played Batman. The film was released in 1989 and helped establish a darker, large-scale superhero style for mainstream cinema. Its Joker combines organized-crime roots with flamboyant theatricality and black comedy.