Joker: Folie à Deux is a 2024 American jukebox musical psychological thriller film directed by Todd Phillips from a screenplay he co-wrote with Scott Silver. Loosely based on DC Comics characters, it is a sequel to Joker (2019). Joaquin Phoenix reprises his role as the Joker, with Lady Gaga as his love interest, Lee Quinzel. Zazie Beetz and Leigh Gill also reprise their roles, while Brendan Gleeson, Catherine Keener, Steve Coogan and Harry Lawtey join the cast. It is produced by Warner Bros. Pictures in association with Joint Effort and was distributed by Warner Bros. Pictures.

Joker was conceived as a standalone film, although Warner Bros. intended the film to launch a DC Black film series. Phillips, director of Joker, expressed interest in making a sequel, which was announced in June 2022, with Gaga and Beetz joining later that year. Principal photography took place in New York City, Los Angeles, and Belleville, New Jersey, from December 2022 to April 2023.

Joker: Folie à Deux premiered at the 81st Venice International Film Festival on September 4, 2024, and was released in the United States on October 4. The film was a critical and commercial failure, having grossed $206 million on a $190–200 million budget, with projections of a $125–200 million loss for Warner Bros.