Days of Future Past is a storyline which ran in Uncanny X-Men #141-142 set in Earth-811 where most of Earth's mutants have been killed.
In this future, Rachel Summers psychically sends an adult version of Kitty Pryde known as Kate Pryde back in time to the 1980 in order to avert the events that ravaged their world. She reveals that in October 1980, Mystique and the Brotherhood of Evil Mutants will assassinate a presidential candidate named Robert Kelly, who is known for his anti-mutant views. Kelly's death will lead to a massive uptake in anti-mutant hysteria, which will eventually cause the U.S. government to reactive the Sentinel program. Programmed to protect humanity from the "mutant menace," the Sentinels will go on to eradicate or imprison most of the mutants in the United States, as well as non-mutant superheroes like the Fantastic Four and the Avengers. In addition to eliminating mutants, the Sentinels will go on to target ordinary humans who might possibly carry the mutant gene, leading to a complete fascist overthrow of the United States.
With the fate of the world on the line, the X-Men rush to Washington, D.C. to save Kelly from the Brotherhood.
In 2001, X-Men #141 was named #25 on the list of Marvel greatest comics of all time.
Marvel Girl, Nimrod and Ahab originate from this reality.
- In 2014, the comic book storyline was loosely adapted as a live-action film called X-Men: Days of Future Past. The film maintains the basic premise of the original story, but makes several key changes. Taking place after the events of X-Men: The Last Stand, the film opens in the year 2023, where the last surviving members of the X-Men seek to survive after the Sentinels have captured or killed most of the world's mutant population. It is discovered that the past event that eventually led to the dystopian future was when Mystique assassinated Bolivar Trask in 1973. In a major departure from the original storyline, Kitty Pryde is not the X-Man who is sent back to the past, but instead she uses her new secondary mutation to send Wolverine's mind back into his 1973 body.
- The comic was adapted into a two-part storyline in X-Men: The Animated Series. Though the basic premise of the original story was retained, the TV show had Bishop as the mutant who travels back to the present in order to prevent Senator Kelly's assassination. The TV series also combined the "Days of Future Past" story with the ongoing X-Traitor plot point from the 90s comics, with Bishop mistakenly believing that Gambit is the one responsible for Kelly's murder.
- Elements of the "Days of the Future Past" storyline are used in Wolverine and the X-Men, which sees a future version of Professor Xavier sending the X-Men a warning from the future about a cataclysmic event that will lead to a future dominated by the Sentinels. The main plot of the first (and only) season revolves around the X-Men trying to prevent this event from occurring so that the post-apocalyptic future Xavier warned them about can never occur.
- The Ultimate Spider-Man episode "Game Over" features a "Days of Future Past"-themed level in Arcade's Murderworld amusement park.
- The video game adaptation of X-Men Origins: Wolverine features a unique framing device not seen in the actual movie, inspired by the "Days of Future Past" comic book. The ending of the game reveals that Wolverine has been reminiscing about his past while living in a dystopian future where Bolivar Trask's Sentinels have launched a campaign of all-out genocide against the world's mutants. Despite the bleak state of the world, Logan vows to keep on fighting.
- Marvel vs. Capcom 3 features a "Days of Future Past" stage, complete with a recreation of the wanted poster seen on the cover of Uncanny X-Men #141.
- A mobile game called Uncanny X-Men: Days of Future Past was released for iOS and Android devices.
- The "Days of Future Past" version of Wolverine was featured in ToyBiz's Marvel Legends line as part of the Legendary Riders wave. The figure came packaged with a reprint of Uncanny X-Men #141.
- The "Days of Future Past" version of Wolverine was featured in Diamond Select's Marvel Select line. It also came packaged with a figure of Kate Pryde and a diorama display base depicting the brick wall and wanted poster from the cover of Uncanny X-Men #141.
- "Days of Future Past" was the subject of a series in the HeroClix figure game. The series featured figurines of the various characters from the comic, such as Wolverine, Kate Pryde, Mystique, Rachel Summers and the Sentinels. A box set featuring a new Sentinel, Rachel Summers and Wolverine was later released.
- Diamond Select released a Minimates box set based on the storyline, which featured Wolverine, Kate Pryde, Mystique and a Sentinel.
- Dynamic Forces released a "Days of Future Past" diorama featuring Wolverine and Kate Pryde.
- Hasbro released a Marvel Legends box set based on the storyline, which included Wolverine and a Sentinel.