Harlequin is an album by the American singer-songwriter Lady Gaga, released on September 27, 2024, by Interscope Records. It is inspired by the musical thriller film Joker: Folie à Deux (2024), in which Gaga portrays the DC Comics character Harley Quinn.

Gaga stated that Harlequin serves as a "companion album" to the film, while some publications have referred to it as a soundtrack album, besides the film's official soundtrack released a week later. Thematically, however, critics described Harlequin as a concept album about Harley Quinn, depicting the supervillain from Gaga's perspective. The album consists of covers of American jazz standards featured on the official soundtrack, as well as two original songs by Gaga, expanding her venture into jazz music following her collaborative albums with American jazz singer Tony Bennett—Cheek to Cheek (2015) and Love for Sale (2021). Gaga characterized Harlequin as a "vintage pop" album.

Upon release, Harlequin received mostly positive reviews from music critics, who praised Gaga's syncretic interpretation of Harley Quinn and the Great American Songbook but felt the album was not much of a creative departure from her works with Bennett. Commercially, Harlequin has reached the top 10 in Austria, France, Germany, Scotland, Spain and Switzerland as well as the top 20 in Belgium Wallonia, Italy, Sweden, the United Kingdom, and the United States. Additionally, it topped the US Jazz Albums chart, marking Gaga's third number-one album there.