Joker: Folie à Deux is a 2024 American musical psychological thriller film directed by Todd Phillips from a screenplay co-written with Scott Silver. It is the sequel to Joker (2019), loosely based on DC Comics characters, and stars Joaquin Phoenix reprising his role as the Joker with Lady Gaga joining the cast as his love interest Harley Quinn. Zazie Beetz also reprises her role from the previous film, while Brendan Gleeson and Catherine Keener also join the cast. It is produced by Warner Bros. Pictures and DC Studios in association with Joint Effort.

Joker was conceived as a standalone film, although Warner Bros. intended for the film to launch a DC Black film series. Phillips expressed interest in making a sequel but confirmed that Joker was not set up to have one. The sequel entered development 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 is scheduled to be released in the United States on October 4, 2024. The film received mixed reviews from critics, who praised the production design, costumes, musical sequences, and the performances of Phoenix and Gaga, but criticized the screenplay, character development, and themes.