The Fox X-Men Film Universe, set on Earth-10005, has begun colliding with the Disney Marvel Cinematic Universe, which is set on Earth-616 (which is sometimes referred to as Earth-199999). Here’s how the X-Men continuity works best IMO.
X-Men: First Class (June 3, 2011)
This film is set in another alternate universe, known as Earth-10005. The mainline M.C.U. Infinity Saga entries were all set on Earth-616 (which is also sometimes referred to as Earth-199999).
Set in 1944 & 1962, this film launches the X-Men film universe which is made up of 13 live action films and connected to several TV series. Several characters introduced here later appear in mainline M.C.U. films and series, including such entries as “Doctor Strange in the Multiverse of Madness”, “Deadpool & Wolverine”, “The Marvels”, “Avengers: Doomsday” & “Avengers: Secret Wars”.
X-Men Origins: Wolverine (May 1, 2009)
Set on Earth-10005, mainly in 1979, the film also features sequences set in 1845, 1861-1865, 1917-1918, 1944-1945, 1969-1971 & 1973.
Danny Huston plays William Stryker, the son of Agent Stryker, who was played in “First Class” by Don Creech.
X-Men (July 14, 2000)
Set in early 1994 (before March 28): Almost 15 years after the 1979 events in “X-Men Origins: Wolverine”. The film opens with a flashback to 50 years before in 1944, which were previously explored in “X-Men: First Class”.
“Logan, it’s been almost fifteen years, hasn’t it?” – Professor X
X2: X-Men United (May 2, 2003)
Set in 1994 (after March 28). Logan is at the location he departed for in the first film and Scott mentions that Jean hasn’t been the same since Liberty Island, seemingly referencing events from the first film as a recent event. The song “Bye Bye Bye” by NSYNC plays in the film; the song was released on our Earth in the year 2000, but must have been released on Earth-10005 (where the X-Men films take place) a few years earlier.
The line “I haven’t seen you in 15 years” is spoken by Stryker (played by Brian Cox) to Wolverine in the film and is a reference to the events depicted in “X-Men Origins: Wolverine”, set in early 1979.
X-Men: The Last Stand (May 26, 2006)
Set in 1995. Time has passed since X2 but not too much time. Also, the film opens with a scene set 20 years before this film in which Xavier meets Jean Grey for the first time. In the later “Dark Phoenix” film, which covers some of the same story points, Jean and Xavier meet in 1975. Placing “X-Men: The Last Stand” in 1995 confirms that parallel multiversal story point.
The Wolverine (July 26, 2013)
Set in 2013, 18 years after “X-Men: The Last Stand”. The film features a credit scene set 2 years later, in 2015. The TV series “The Gifted”, which begins in 2017, is viewed by some as the next installment in this timeline. The next film in the cycle (“Days of Future Past”) begins in 2023.
The Gifted (October 2, 2017 – February 26, 2019)
The series seems to be set in a contained parallel universe in which the X-Men have disappeared and further generations of mutants are having to fend for themselves. The series begins in the Spring of 2017 and it has been theorized by some (including by some of the creative team) that this is the same timeline that leads to the events in the later film, “X-Men: Days of Future Past”, which would make this an extension of the X-Men films up to this point.
Season 1 seems to take place from April to May of 2017. All of the dates in Season 2 (which supposedly takes place 6 months after Season 1) are repeatedly shown to be in 2018.
While the series can fit in with the films, it doesn’t feature the same characters and it doesn’t actually crossover with the films, which just means this series can be a fun addition, but it is not an essential piece of the puzzle.
X-Men: Days of Future Past (May 23, 2014)
In a story that mirrors “Avengers: Endgame”, beginning in 2023, Wolverine travels back in time to 1973 to change the X-Men timeline to prevent a horrific future where many X-Men have died.
I highly recommend viewing the superior Rogue Cut of the film, which is the only version I will watch. It can be viewed on Amazon Prime.
X-Men: Apocalypse (May 27, 2016)
The new X-Men Timeline continues to unfold with the main storyline set in 1983, after a prologue set in 3600 BC, expanding on the post-credit scene from “Days of Future Past”.
A credit scene in this film sets up the events of “Logan”.
X-Men: Dark Phoenix (June 7, 2019)
The X-Men Timeline continues to unfold with the main story now set in 1992, after a prologue set in 1975.
Deadpool (February 12, 2016)
The film is set in 2016 and features this timeline’s version of Wade Wilson / Deadpool (again played by Ryan Reynolds), the X-Men Mansion and Colossus.
The next Deadpool film is set in 2018, but we have to jump ahead for a bit first. Trust me.
The New Mutants (August 28, 2020)
Set in 2027 or 2028 along with concurrent events which are later seen as having taken place before “Logan” in 2029.
Logan (March 3, 2017)
Set in 2029.
Deadpool 2 (May 18, 2018)
Set in 2018 with cameos by the surviving X-Men from “X-Men: Dark Phoenix” and commenting on the events of “Logan”, this film wraps up Fox’s X-Men series of films – until they crossover with the Marvel Cinematic Universe.
WandaVision (January 15 – March 5, 2021)
Set in the mainline 616 / Earth-199999 universe, this miniseries begins 3 weeks after the events of “Avengers: Endgame” in late 2023.
Evan Peters plays an alternate version of Wanda’s twin brother, Pietro Maximoff / Quicksilver, previously played by Aaron Taylor-Johnson in “Avengers: Age of Ultron”. Peters had played the Fox X-Men version of the same character, Peter Maximoff / Quicksilver in “X-Men: Days of Future Past”, “X-Men: Apocalypse”, “X-Men: Dark Phoenix” & “Deadpool 2”.
Doctor Strange in the Multiverse of Madness (May 6, 2022)
Set in late 2024, the film follows up on “WandaVision” and features Sir Patrick Stewart as a variant of Professor Charles Xavier.
Deadpool & Wolverine (July 26, 2024)
The X-Men Universe crosses-over with the Marvel Cinematic Universe, featuring many returning characters. The main events of this story are set in late 2024, after “Doctor Strange in the Multiverse of Madness”.
The Marvels (November 10, 2023)
The film is set from November 19 to November 20 of 2026 and while unclear until the ending, the entire film seems to be setting up another crossover with the X-Men.
Agatha All Along (September 18 – October 30, 2024)
This series is set from November 20 to November 22, 2026, picking up 3 years after “WandaVision” and 2 years after “Doctor Strange in the Multiverse of Madness”, featuring the return of Evan Peters as Ralph Bohner, the possible Pietro / Peter Maximoff variant.
Avengers: Doomsday (December 17, 2026)
The upcoming Avengers sequel will features a major clash between the X-Men and the Avengers.
Returning X-Men Characters Include: (SPOILERS)
Patrick Stewart as Charles Xavier / Professor X
Ian McKellen as Erik Lehnsherr / Magneto
Rebecca Romijn as Raven Darkhölme / Mystique
Kelsey Grammer as Hank McCoy / Beast
Hugh Jackman as Logan / Wolverine
Ryan Reynolds as Wade Wilson / Deadpool
Channing Tatum as Remy LeBeau / Gambit
James Marsden as Scott Summers / Cyclops
Alan Cumming as Kurt Wagner / Nightcrawler