X-Men in film dates back to as early as 1994, when 20th Century Fox acquired the feature film and television rights to the team from Marvel for $2.6 million USD after several unsuccessful attempts to adapt the characters at other film studios and distributors throughout the prior decade. Fox released X-Men in 2000 to critical and commercial success, with the film being credited for rejuvenating mainstream interest in movies featuring and adapting comic book characters alongside other licensed Marvel films released earlier in the decade. X-Men's success allowed the studio to launch a film franchise centered on the team and associated characters which included a trilogy with the initial cast until 2006, four prequel films (2011-19), a trilogy of Wolverine films (2009-2017), two Deadpool films (2016-18) and the spin-off film The New Mutants (2020), which concluded 20th Century Fox's franchise after a two-decade run.

In 2005, Marvel Studios was formed as an independent arm of the company that intended to house the production of various films using Marvel Comics characters, leading to the creation of the Marvel Cinematic Universe (MCU) franchise. Marvel was later acquired by The Walt Disney Company in December 2009 for $4 billion USD, but did not regain the film rights to the X-Men comic books due to Fox's existing licensing deal, barring the team and associated characters from appearing in the MCU or other internally-produced Marvel media. In March 2019, Disney completed their acquisition of 21st Century Fox for a final total of $71.3 billion USD in order to secure 20th Century Fox's various entertainment licenses, including the film rights to the X-Men alongside the Fantastic Four and Deadpool. Control over the characters' film appearances was transferred to Marvel Studios, leading to multiple Marvel-based films at Fox to be stalled and subsequently cancelled, with plans to instead integrate the respective properties into the MCU franchise.

In 1982, Nelvana optioned the film rights to the X-Men comics from Marvel Entertainment. As early as 1979, Marvel's former vice president of business affairs Alice Donnenfeld Vernoux, had been tasked by former editor-in-chief Stan Lee with attempting to license off various Marvel Comics properties for adaptation in film and television in light of recent blockbuster successes such as Jaws (1975), Star Wars (1977) and Superman (1978). Nelvana founder Michael Hirsh had expressed significant interest in adapting X-Men for live-action film as a fan of the source material, and Nelvana, a studio primarily known for animated television, was similarly transitioning towards theatrical releases with their first animated feature Rock & Rule (1983). ^[1] The deal between Marvel and Nelvana stipulated that the latter studio would handle production duties on the film, while Marvel would handle responsibilities in merchandising and promotion. ^[2]

Uncanny X-Men and New Mutants writer Chris Claremont was hired by Hirsh to pen the film's screenplay, ultimately producing two story outlines. Both outlines featured a team roster comprising Cyclops, Jean Grey, Storm and Wolverine alongside Professor X and Kitty Pryde as a new member. ^[3] The first version of the film, tentatively titled Rite of Passage and dated for June 1982, featured Kitty Pryde as the audience surrogate character as she navigated the X-Men's world and came into conflict with her father, who became possessed by the mutant Proteus and exercised his political influence to incite mutant prejudice. Pryde would've helped the X-Men save a captive Xavier and redeem her father by the end of the film. The second outline, dated for 1983, de-emphasized Pryde's significance in favor of a plot that broadly explored the physical and ideological conflict between the X-Men and their adversaries, the Brotherhood of Mutants led by Magneto. Set during the Cold War, the narrative would've depicted Magneto using his powers to, raise an island from the ocean, destroy a Soviet submarine, and set off a volcano as an intimidation tactic. His tactics would've almost resulted in Pryde's death, at which point he saw the errors of his ways and sought redemption by the film's conclusion. ^{[4] [5]}

The film's production eventually stalled as Claremont chose to prioritize his work on the X-Men comic books in addition to writing novels. Nelvana then brought on Marvel Comics writers Roy Thomas and Gerry Conway to take over scripting duties, with Conway later admitting he wasn't aware of Claremont's prior involvement. ^[6] At this point in the project, Nelvana had secured a deal to distribute the film through Orion Pictures, and two producers had boarded the project. Thomas and Conway's first draft combined elements across Claremont's two previous outlines, including Kitty as the primary point-of-view character for the world of mutants and Proteus as the primary antagonist from the first treatment, as well as a battle between the X-Men and Magneto's Brotherhood from the second treatment. ^[7] According to Conway, the attached producers were dissatisfied with their initial draft and had commissioned a rewrite that notably deviated further from the source material than originally intended, removing elements previously present such as the X-Mansion, the social commentary on mutant injustices, and the omission of any references or terminology related to mutants entirely due to the implicit comparison to monsters which would've made the film harder to market as an allegory for marginalization. Jean Grey's presence in the film was replaced with an original character with the power of transforming materials as a team member, inspired by Japanese New Wave cinema in an attempt to market the film towards Japanese investors. Bernie, another original character, was written into the film as a sidekick for Kitty Pryde in order to pivot the film's focus away from her in favor of capturing more interest from a younger male audience. ^[8] The film would ultimately cease production due to Orion Pictures' ongoing financial troubles throughout 1985, leading Nelvana to eventually relinquish the character rights to Marvel. ^[9]

Following the critical and commercial success of the Warner Bros. Pictures film Batman (1989), Marvel sought to rejuvenate interest in licensing out their comic book properties for film adaptation, with filmmaker James Cameron being approached to produce a live-action X-Men film for Carolco Pictures through his production studio Lightstorm Entertainment. Cameron's then-wife Kathryn Bigelow was expected to direct the film, while Gary Goldman had been attached to write the screenplay. ^[10] Goldman's script, tentatively titled Wolverine and the X-Men, depicted Logan recruiting Kitty Pryde into the X-Men alongside Jean Grey, Cyclops, Nightcrawler and Mastermind, all of whom are now facilitated at "Exton Academy" as opposed to Xavier's School for Gifted Youngsters. The plot would've involved the X-Men's confrontation with a wealthy socialite and preacher Tommy Prince, who would've assembled "The Citizens' Crusade" to incite anti-mutant sympathies from the general public, at which point Mastermind would betray the team to side with his ideologies. ^[11] Prince would later be revealed to be disguising his own mutant heritage, being depicted as an original take on the Magneto character with similar powers and a motivation to oppress humanity. ^[12] X-Men writer Chris Claremont later recalled that in attempting to engage James Cameron on the film, the film was immediately de-prioritized as soon as Stan Lee instead inquired him on his interest in adapting Spider-Man to film. Kathryn Bigelow later produced her own treatment for an X-Men film unrelated to Goldman's screenplay, with the intent of casting Bob Hoskins and Angela Bassett as Wolverine and Storm, respectively, but it was immediately dismissed due to Cameron's increased interest in a Spider-Man feature. ^{[13] [14]} Cameron's Spider-Man film would similarly never materialize as a result of Carolco becoming embroiled in a dispute over the ownership of the character's film rights between themselves, Marvel and distributor 21st Century Films, before all three entities declared bankruptcy, with both the X-Men and Spider-Man feature film rights reverting to Marvel upon their re-emergence in the late 1990's. ^[15]

Marvel entered early discussions with Columbia Pictures regarding a live-action X-Men film in 1992 just as the studio was also entering development on a Black Panther film, but the movie didn't materialize past these conversations. ^[16] Instead, 20th Century Fox separately engaged Marvel about acquiring the character rights, having been impressed by the success of X-Men: The Animated Series (1992-97) on their sister network Fox Kids during syndication, and film producer Lauren Shuler Donner successfully acquired the license to develop the film at Fox in 1994. ^[17] Donner brought on Andrew Kevin Walker to screenwrite the project, with two drafts of the script delivered by the following June. Walker's storyline involved the government initiating the Mutant Registration Act in response to a terrorist attack orchestrated by Magneto and his Brotherhood of Mutants, which comprised of Toad, Blob, Sabretooth and Juggernaut, who would be broken out of Ryker's Island by the trio and recruited into their ranks. The film would heavily center around the X-Men (Cyclops, Jean Grey, Beast, Iceman and Angel) and their efforts to recruit Wolverine and Jubilee, as well as the human antagonists Bolivar Trask and Henry Peter Gyrich, as the pair construct Sentinels to eliminate mutants. ^[18] The screenplay also included other elements of the comics such as Department H being Wolverine and Sabretooth's former unit in Canada, the X-Copter, the Danger Room training facility, the Vault as a supermax prison for superhumans, and Magneto establishing a safe haven for mutants conceptually similar to Genosha after taking over Manhattan. ^[19] Film producer Laeta Kalogridis performed rewrites on Walker's story throughout 1995, and introduced Storm to the team roster, setting up a subplot exploring a potential romantic relationship with Wolverine. ^[20] Author and Spider-Man 2 (2004) co-screenwriter Michael Chabon submitted his own treatment to Fox in 1996, which featured a team roster of Professor X, Cyclops, Jean Grey, Beast, Iceman, Nightcrawler and Storm, and omitted the Brotherhood of Mutants as antagonists in favor of setting them up in a potential sequel. ^[21]