Joker is a 2019 American psychological thriller film directed by Todd Phillips, who co-wrote the screenplay with Scott Silver. The film, based on DC Comics characters, stars Joaquin Phoenix as the Joker. An origin story set in 1981, the film follows Arthur Fleck, a failed stand-up comedian who turns to a life of crime and chaos in Gotham City. Robert De Niro, Zazie Beetz, Frances Conroy, Brett Cullen, Glenn Fleshler, Bill Camp, Shea Whigham, and Marc Maron appear in supporting roles. Joker was produced by Warner Bros. Pictures in association with Bron Creative and Village Roadshow Pictures, and distributed by Warner Bros.

Phillips conceived Joker in 2016 and wrote the script with Silver throughout 2017. The two were inspired by 1970s character studies and the films of Martin Scorsese, who was initially attached to the project as a producer. The graphic novel Batman: The Killing Joke (1988) was the basis for the premise, but Phillips and Silver otherwise did not look to specific comics for inspiration. Phoenix became attached in February 2018 and was cast that July, while the majority of the cast signed on by August. Principal photography took place in New York City, Jersey City, and Newark, from September to December 2018. It is the first live-action theatrical Batman film to receive an R-rating from the Motion Picture Association of America, due to its violent and disturbing content.

Joker premiered at the 76th Venice International Film Festival on August 31, 2019, where it won the Golden Lion, and was released in the United States on October 4, 2019. The film polarized critics; while Phoenix's performance was praised, the dark tone, portrayal of mental illness, and handling of violence divided responses.^[6] Joker also generated concerns of inspiring real-world violence; the movie theater where the 2012 Aurora, Colorado mass shooting occurred during a screening of The Dark Knight Rises refused to show it. The film has grossed $548.3 million worldwide, making it the tenth highest-grossing film of 2019, and set box office records for an October release.