Many DC fans were saddened by the news that Warner Brothers Discovery would not be releasing Batgirl. However, some good news comes along with it as the release date for Joker: Folie a Deux (Madness for Two) has been revealed. The sequel to the blockbuster comic book film will be hitting theaters on 4 October 2024, on the five-year anniversary of the first film.

Joker was intended to be a standalone film with no sequels. But in August 2019, Phillips stated that he would be interested in making a sequel, depending on the film's performance and Joaquin Phoenix's interest. In June 2022, the sequel was officially confirmed to be in development with Phillips serving as director with a script he co-wrote with Silver. The working title of the project was revealed to be Joker: Folie a Deux. Lady Gaga reportedly was in negotiations to star alongside Phoenix as Harley Quinn, and it was also reported that the film would be a movie musical.

It 2019 prequel Joker was a psychological thriller directed by Todd Phillips based on DC Comics characters, starring Joaquin Phoenix in the titular role. The film provided a possible origin story for the Clown Prince of Crime. It follows Arthur Fleck, a failed clown and aspiring stand-up comedian whose descent into insanity and nihilism inspires a violent counter cultural revolution against the wealthy in a decaying Gotham City. 

Joker received positive reviews from critics, earning praise for Phoenix's performance, direction, visual style, editing, musical score, and cinematography. The film was an instant box office success given the character's immense popularity due to its various iterations over the years. Joker also went on to receive numerous accolades including the awards for Best Actor for Phoenix and Best Original Score at the 92nd Academy Awards. The film ended its run by grossing over $1 billion at the worldwide box office, becoming the first R-rated movie to do so.