Justice League is a 2017 American superhero film based on the DC Comics superhero team of the same name. Produced by Warner Bros. Pictures, DC Films, RatPac-Dune Entertainment, Atlas Entertainment, and Cruel and Unusual Films, and distributed by Warner Bros. Pictures, it is the fifth installment in the DC Extended Universe (DCEU). Directed by Zack Snyder, who was replaced by Joss Whedon after Snyder left the project, and written by Chris Terrio and Whedon, the film features an ensemble cast including Ben Affleck, Henry Cavill, Gal Gadot, Ezra Miller, Jason Momoa, Ray Fisher, Amy Adams, Jeremy Irons, Diane Lane, Connie Nielsen, and J. K. Simmons. In the film, following the events of Batman v Superman: Dawn of Justice (2016), Batman and Wonder Woman recruit The Flash, Aquaman, and Cyborg after the death of Superman to save the world from the catastrophic threat of Steppenwolf and his army of Parademons.

Warner Bros. began to develop a live-action Justice League film in 2007 with George Miller set to direct, but the project was canceled due to production delays and budgetary concerns. Principal photography took place from April to October 2016. After Snyder stepped down from the film following the death of his daughter, Whedon was hired to oversee the remainder of post-production, including writing and directing additional scenes, as well as reshooting a large portion of the film, which changed many aspects of it; Snyder ultimately retained sole credit as director. With an estimated production budget of $300 million, Justice League is one of the most expensive films ever made.

Justice League premiered at the Dolby Theatre in Hollywood, Los Angeles on November 13, 2017, and was released in the United States four days later. The film received mixed reviews from critics, and grossed $661.3 million worldwide against an assumed break-even point of $750 million, becoming a box-office bomb and losing Warner Bros. an estimated $60 million. Whedon's major involvement during post-production also received harsh criticism, including from cast members such as Gadot and Fisher. A director's cut, titled Zack Snyder's Justice League, was released on HBO Max in 2021, following a fan campaign that advocated for Snyder's vision for the film.