X-Men: Days of Future Past (2014)

In a dystopian future, Sentinels have been programmed to identify and hunt down mutants and any humans who help them. In Moscow, they attack a small band of X-Men survivors consisting of Kitty Pryde, Colossus, Blink, Warpath, Bishop, Iceman and Sunspot, but Kitty sends Bishop’s consciousness back in time a few days to warn the others as to ensure their survival. The group retreats to a remote Chinese temple where they meet with Storm, Wolverine, Professor Charles Xavier, and Magneto. Xavier explains the history of the Sentinels, which were designed by Bolivar Trask, a military scientist whom Raven Darkhölme assassinated in 1973. In response, government forces captured Raven and experimented on her, using her DNA to advance the Sentinel program, allowing Sentinels to adapt to nearly every mutant power.

Xavier plans to go back in time and prevent Trask’s assassination in hopes of changing their future but since Xavier would not survive going back decades, Wolverine volunteers instead because his regenerative powers allow him to survive the process. Awakening in his younger body in 1973, Wolverine goes to the X-Mansion, learning from Hank McCoy that the school has been closed for years due to many students and staff being drafted into the Vietnam War, and Lehnsherr (Magneto) being falsely arrested for assassinating fellow mutant John F. Kennedy. A young, broken Xavier turned to alcoholism and frequently uses a specialized serum that allows him to walk but suppresses his telepathic abilities. Hoping to reunite with Mystique, Xavier agrees to help Wolverine. The trio infiltrate The Pentagon and break Lehnsherr out of prison, aided by the newly recruited Peter Maximoff.