Various films were in development at 20th Century Fox for the X-Men film franchise. Due to production delays and the acquisition of 21st Century Fox by The Walt Disney Company, many of the planned films were never made.
X-Men Origins: Magneto
In December 2004, 20th Century Fox hired screenwriter Sheldon Turner to draft a spin-off X-Men film, and he chose to write Magneto, pitching it as "The Pianist meets X-Men." In April 2007, David S. Goyer was hired to direct. Turner said the script was set from 1939 to 1955,and it follows Magneto trying to survive in Auschwitz. He meets Xavier, a young soldier, during the liberation of the camp. He hunts down the Nazi war criminals who tortured him, and this lust for vengeance turns him and Xavier into enemies.
In May 2006, Ian McKellen said he would reprise the role using the computer-generated facelift applied to him in the prologue of X-Men: The Last Stand. Lauren Shuler Donner stated that the film would need McKellen to anchor the story, which would take place in flashbacks. With Goyer's hiring in 2007, it was said actors in their twenties would play the characters. McKellen reiterated his hope to open and close the film in July 2008.  The film was planned to shoot in Australia for a 2009 release,but it was delayed by the 2007-2008 Writers Guild of America strike. In April 2008, concept art, including one of a younger Beast, was being designed.
In June 2008 the X-Men Origins prefix also applied to Wolverine was confirmed, and the project was seeking approval to film in Washington, D.C. By December 2008, Goyer said filming would begin if Wolverine was successful. The story was moved forward to 1962, and involves Xavier and Magneto battling a villain.  Ian McKellen confirmed that he would not be reprising his role as Magneto, citing his age as a barrier.
In 2009, X-Men's producer Lauren Shuler Donner stated that the movie may never be made.Donner also said that "the studio has a wealth of potential stories, and they have to stand back and decide which ones to make. And Magneto, I think, is at the back of the queue. Maybe it'll get made in five years – who knows?"Both Donner and Bryan Singer have stated that Magneto will probably not be produced, as the plot of X-Men: First Class "supersedes" the story of the planned film and that many ideas from the film were incorporated into First Class already. 
In July 2013, Jeff Wadlow was hired to write and direct a film adaptation of the X-Men spin-off comic-book series X-Force. Mark Millar, the creative consultant for 20th Century Fox's Marvel Comics based films at the time, stated that the film would feature five characters as protagonists. After the release of Deadpool, Ryan Reynolds said that Deadpool would appear in the film.
By May 2016, Simon Kinberg was in the process of rewriting the script. In February 2017, Joe Carnahan had signed on as director, as well as a co-writer with Reynolds. By September of the same year, Drew Goddard was attached to write and direct. Rhett Reese said the film would be a R-rated take on the X-Men. Kinberg, Reynolds and Donner will produce the film. In September 2018, Kinberg said that Goddard would begin work on the script after the release of Bad Times at the El Royale.
The New Mutants sequels
Alpha Flight and Exiles
X-Men: Fear the Beast
X-Men: Fear the Beast was the title of a spin-off film pitched by Byron Burton, former assistant to editor/composer John Ottman while he was working on X-Men: Apocalypse. Ottman was skeptical of the idea that Beast could carry his own film, but when Burton said he could complete a script in two weeks, Ottman gave the aspiring screenwriter a chance to prove the idea could work.
After reading Burton's draft, Ottman decided to join the project and rework the script as a $90 million film. Fear the Beast would have been set in the late '80s, opening in a snow-covered Inuit village that was being stalked by a mysterious creature. Ottman likened the film to John Carpenter's The Thing, due to both settings involving an "inhospitable environment". The story would then jump forward to Hank McCoy living in the X-Mansion, where he would be struggling to keep his mutation under control with a serum that was introduced in X-Men: Days of Future Past. His beastly nature surfaced during a Danger Room sequence, where the "Friends of Humanity" would have also made an appearance. Early in the first act, it would be revealed that Hank had been helping a scientist with a similar mutation.
Hank provided the scientist with a sample of his serum, but would later discover that the man was the one terrorizing the Inuit village at the start of the film. It would culminate in a showdown where Hank teamed up with Wolverine, who was located by Professor X using Cerebro. Fear the Beast ended with a tease of Mister Sinister having watched all of the proceedings. This was going to be a set up to Sinister being a multi-film villain orchestrating things.
Ottman passed the idea around to people at 20th Century Fox, but because Fear the Beast involved core X-Men characters such as Professor X and Beast, the film would needed to be signed off by Simon Kinberg. Kinberg was the key architect behind the X-Men films and was working on Dark Phoenix at the time. He politely declined to read the script to avoid being influenced by it, as he had plans to reintroduce Wolverine into the X-Men films after Hugh Jackman retired from the role. As such, Wolverine being used in any other film would have muddled Kinberg's plans. However, Ottman didn't mind as he would have pushed to direct the film himself had Fox been interested.
Ottman was constantly reworking the script to avoid any problems that would have showed up in post-production. Both Ottman and Burton noted that the version of Fear the Beast they originally pitched was an early draft that would have changed over time.
An outline of an Omega Red film was written by Byron Burton and John Ottman. It was planned to be a follow-up to X-Men: Fear the Best, which teased Mister Sinister as a multi-arc villain orchestrating events behind-the-scenes. It would have been set in the late '80s and involved Sinister testing the X-Men.
A film based on X-23 likely set after Logan, had began production in 2018 with James Mangold returning to direct, and X-23 creator Craig Kyle writing the script. It had gotten to the script writing stage before the Disney buyout.
Fantastic 4 vs X-Men
In 2016, Simon Kinberg expressed his interest in having a crossover between the Fantastic 4, and the X-Men which would have seen the two teams fighting each other over differing ideals. After the failure of Fantastic 4 (2015), the film was shelved.
X-Men/Fantastic 4/Deadpool/Daredevil Crossover
In 2011 First Class writers Ashley Edward Miller and Zack Stentz were hired to write a script featuring all the Marvel characters Fox had access to including the X-Men, Fantastic Four, Daredevil, and Deadpool. The script would have involved: “Johnny Storm go supernova while trying to apprehend the villain Molecule Man. This would result in him accidentally blowing a hole in Manhattan and in response to the carnage, the government is forced to introduce the superhero registration act.
The heroes from both teams would be split on opposing sides, and one of the key fights was set to feature Wolverine (Hugh Jackman) taking on Mr. Fantastic, a battle that would end with Reed Richards pinning Wolverine down, extending his hands until they're one molecule wide, and then, using them as scissors to cut Logan's arms off.
After a series of equally intense events, the heroes eventually make peace with one another, and the post-credits scene would've set up the next film with the tease of a Super Skrull invasion. ” Paul Greengrass was being courted to direct but was unable to come to a deal with Fox. After the success of First Class and the script of Days of Future Past being written instead, this movie was passed and Fox decided to give the Fantastic 4 their own reboot. 
X-Men: First Class direct sequel
While director Matthew Vaughn was still signed on to do sequels to X-Men: First Class, his plan was to do a film set in the 1970s that featured the First Class characters and a younger version of Wolverine, who would have been played by Tom Hardy or another actor. Days of Future Past was planned as the finale to the trilogy, which involved Patrick Stewart and Ian McKellen reprising their roles for the film.
However, when Vaughn completed the Days of Future Past script and presented it to 20th Century Fox, the studio liked it so much that they decided to immediately go ahead with Days of Future Past as the sequel to First Class instead of Vaughn's original idea. This was one of the reasons why Vaughn left the X-Men films to work on Kingsman instead, as he felt that the film executives were rushing to do Days of Future Past instead of building up to it properly.
- ↑ https://screenrant.com/plot-synopsis-x-men-origins-magneto/
- ↑ https://www.denofgeek.com/us/movies/x-men/235939/x-men-movies-you-never-saw
- ↑ http://www.worstpreviews.com/headline.php?id=18789
- ↑ 'Kick-Ass 2' Filmmaker Tackling Fox's 'X-Force'
- ↑ Fox's 'X-Force' Movie Will Feature Five-Person Team, Millar Teases
- ↑ Getting an X-Force Movie Made Is Ryan Reynolds' Next Priority
- ↑ X-Force Movie: Simon Kinberg Writing; Will We See X-23?
- ↑ X-Force Film Gets A Director & Reynolds To Co-Write
- ↑ Drew Goddard To Direct & Write ‘X-Force’ Deadpool leads Black Ops Force
- ↑ Gambit Movie Will be a Romantic Comedy, Says Producer
- ↑ 11.0 11.1 11.2 11.3 11.4 11.5 X-Men: A 'Beast' Spinoff Was Pitched to Fox Before 'Dark Phoenix'
- ↑ https://www.comicbookmovie.com/x-men/x-men-vs-fantastic-four-civil-war-plot-details-revealed-for-massive-crossover-film-that-almost-happened-a168821
- ↑ Exclusive: Matthew Vaughn Talks His Plans for First Class Sequels