Joker: Folie à Deux

Joker (2019) was intended to be a standalone film with no sequels,[10] but Warner Bros. intended for it to launch DC Black, a line of DC Comics-based films unrelated to the DC Extended Universe (DCEU) franchise with darker, more experimental material, similar to the DC Black Label comics publisher.[11][12][13] While director Todd Phillips said in August 2019 that he would be interested in making a sequel, depending on the film's performance and if Phoenix was interested;[14] he later clarified that "the movie's not set up to [have] a sequel. We always pitched it as one movie, and that's it."[15] In October 2019, Phoenix spoke to journalist and Rolling Stone film critic Peter Travers of possibly reprising the role of Arthur, centering on Travers' asking of Phoenix if he considers Joker to be his "dream role." Phoenix stated, "I can't stop thinking about it... if there's something else we can do with Joker that might be interesting,"[16] and concluded, "It's nothing that I really wanted to do prior to working on this movie. I don't know that there is [more to do] ... Because it seemed endless, the possibilities of where we can go with the character."[17] He was paid $20 million for his involvement.[18]

In November 2019, The Hollywood Reporter announced that a sequel was in development, with Phillips, Silver, and Phoenix expected to reprise their duties.[19] However, Deadline Hollywood reported the same day that The Hollywood Reporter's story was false and that negotiations had not even begun yet.[20] Phillips responded to the reports by saying that he had discussed a sequel with Warner Bros. and it remained a possibility, but it was not in development.[21] Phillips also confirmed that The Batman (2022) would not be set in the same continuity as Joker.[22] During an interview with Variety at the Palm Springs International Film Festival, Phillips expressed interest in a spin-off focusing on Batman, saying, "It's a beautiful Gotham. What I would like to see someone tackle is what Batman looks like from that Gotham. I'm not saying I'm going to do that. What was interesting to me about the inclusion of Batman in our movie was 'What kind of Batman does that Gotham make?' That's all I meant by that."[22]

In June 2022, Phillips announced that the sequel was in development, with a script by him and Silver. The film was also revealed to be titled Joker: Folie à Deux.[23][24] Later that month, it was announced Lady Gaga was in talks to portray Harley Quinn and that the film would be a musical.[25] Gaga would confirm her casting later that summer.[26] In August, it was reported Zazie Beetz was in negotiations to reprise her role as Sophie Dumond in the film.[27] Beetz was confirmed to be reprising her role the following month, alongside the cast additions of Brendan Gleeson, Catherine Keener and Jacob Lofland.[6][7][8] Gleeson joined the project out of his admiration for both Phoenix's "indelible" performance in the first film and Gaga, but admitted to being "kinda intimidated" as to what he had to do for his role.[28] In October, Harry Lawtey joined the cast in what Deadline Hollywood reported as a "big role".[9] By February 2023, DC Studios CEO James Gunn confirmed that Folie à Deux would be a DC Elseworlds project, taking place outside the main cinematic DC Universe (DCU).[29]

The abandoned Essex County Isolation Hospital in Belleville, New Jersey (pictured in March 2023, with vintage cars and props) served as a filming location for Arkham State Hospital

Principal photography began on December 10, 2022, with Phillips releasing a first look on his Instagram account.[30] Exterior filming occurred in Los Angeles and New York by March 2023.[31] Arkham Asylum scenes are being filmed at the abandoned Essex County Isolation Hospital.[32] In April 2023, filming took place at the "Joker Stairs", the stairway on West 167th street in the Bronx featured prominently in the first film.[33] Filming officially wrapped on April 4, 2023.[34]