X-Men: Days of Future Past is a 2014 superhero film directed and co-produced by Bryan Singer and written by Simon Kinberg from a story he created with Jane Goldman and Matthew Vaughn. The film is based on the Marvel Comics superhero team the X-Men, the fifth mainline installment of the X-Men film series, a sequel to X-Men: The Last Stand (2006) and X-Men: First Class (2011), a follow-up to The Wolverine (2013), and the seventh installment overall. It stars an ensemble cast, including Hugh Jackman, James McAvoy, Michael Fassbender, Jennifer Lawrence, Halle Berry, Anna Paquin, Elliot Page, Peter Dinklage, Ian McKellen, and Patrick Stewart. The story, inspired by the 1981 Uncanny X-Men storyline "Days of Future Past" by Chris Claremont and John Byrne, focuses on two time periods, with Logan traveling back in time to 1973 to change history and prevent an event that results in unspeakable destruction for both humans and mutants.

Vaughn had directed X-Men: First Class and was set to return in Days of Future Past before leaving for Kingsman: The Secret Service and the 2015 version of Fantastic Four. Thus Singer, who had directed the first two X-Men films, made his return as a director, and brought along most of the crew from those productions. With a budget of $205 million, the film's principal photography began in Montreal, Quebec, in April 2013, and concluded in August the same year, with additional filming and pick-ups taking place in November 2013 and February 2014. Twelve companies handled the visual effects.

X-Men: Days of Future Past premiered in New York City on May 10, 2014, and was theatrically released on May 23 by 20th Century Fox. The film received praise for its story, visual effects, action sequences, acting, and thematic elements. During its theatrical run, the film earned $746 million worldwide, making it the sixth-highest-grossing film of 2014, as well as the third-highest-grossing film in the series behind Deadpool and Deadpool 2. The film received an Academy Award nomination for Best Visual Effects, making it the first X-Men film to be nominated for an Oscar. Two sequels titled X-Men: Apocalypse and Dark Phoenix were released in 2016 and 2019, respectively.