The X-Men are set to join the MCU sometime in the future. While no official project has been announced, with the acquisition of 20th Century Fox by The Walt Disney Company it is only a matter of time before mutants and therefore the X-Men make their way into the MCU. However, when the X-Men finally do join the MCU, Marvel Studios is certainly going to have a difficult time replacing some cast members of the Fox X-Men film series. The franchise had a number of great performances, from Hugh Jackman as Wolverine and Ryan Reynold's Deadpool, to finding two great portrayals of Professor X and Magneto. The franchise also gave the spotlight to a number of popular characters from the comics like Storm, Jean Grey, Beast, and Mystique.
However, the Fox X-Men series also tended to waste a lot of popular characters in the wider X-Men franchise. Despite the nature of the comic being able to showcase a number of memorable characters, the movies tended to focus on four characters: Wolverine, Professor X, Magneto, and Mystique. This meant a lot of fan-favorite characters were underutilized, and often relegated to either extended cameos or one-off film appearances.
With the franchise being reset, this gives the MCU the chance to redo and properly translate some great characters from the comics that the other films ignored. These are the eight X-Men characters that need to find redemption in the MCU.
8 Psylocke (Kwannnon)
This is a tricky one to explain, but in the comics, the character many fans associate with Psylocke is a white British woman named Betty Braddock who had a mind swap with a Japanese mutant ninja named Kwannon, where each of their consciousness was transferred into the other's body. Marvel Comics corrected this in 2018, with Betty being restored to her original body and adopting the moniker of Captain Britain and Kwannon kept the Psylocke mantle.
Psylocke appeared as a minor character in X-Men: The Last Stand with a different powerset but was never named on-screen. Then in 2016, Psylocke was portrayed by Olivia Munn in X-Men: Apocalypse in a larger role, but one that amounted to a one-off appearance. The character's survival was originally intended to amount to a return in X-Men: Dark Phoenix, but the character was written out. As Kwannon has finally been restored to her body in the comics and the mantle of Psylocke, she is the one who should take on the mantle in the MCU.
7 Kitty Pryde
One of the most important members of the X-Men, her character arc from young student to eventually head of the school is one of the most fascinating stories in X-Men lore. Despite her prominence in the comics, the films struggled to find a compelling use for her. Kitty Pryde appeared in two cameo roles in the first two X-Men films before casting Elliot Page in X-Men: The Last Stand and X-Men: Days of Future Past. Yet Pryde was sadly a side character for the most part, and while plans were in place for a solo Kitty Pryde movie were announced, the movie hasn't materialized.
Kitty Pryde fills a number of important functions that could fit into the MCU. The character is an easy POV character for the filmmakers to introduce mutants and the wider X-Men mythos. She is one of the most prominent Jewish characters in Marvel Comics, one element the MCU is actively looking to expand into with the introduction of Moon Knight's Judaism and likely the Thing from Fantastic Four. Also, she is traditionally depicted as a teenager when first introduced, meaning she fits well into the MCU's recent plans to introduce young heroes like Ms. Marvel, America Chavez, and even the MCU Peter Parker.
6 Rogue
Rogue has a long interesting history in the pages of Marvel Comics, as she was originally introduced as a villain and was the adoptive daughter of Mystique (making her the adoptive sister of the X-Men Nightcrawler). Anna Paquin played Rogue in the original X-Men trilogy as a major character, yet despite all the screen time, the character in the film was drastically different from the one that comic book readers or fans of the animated series knew.
The Rogue in the film is a very shy closed-off individual, a creative choice made by the filmmakers as they found the character's abilities a good match with the feeling of isolation the film wanted to convey. While it was a great starting point for the franchise, it felt like the later sequels struggled with what to do with Rogue after they moved beyond her purpose in the first film. In the comics, the character is a much more confident character, and in addition to her absorption powers, she also possesses super strength and flight, powers she acquired in a confrontation with Carol Danvers. With Carol Danvers (played by Brie Larson) being a major part of the MCU, Rogue could be introduced into the MCU and one closer to her comic book counterpart.
5 Apocalypse
One of the X-Men's most powerful villains, Apocalypse is often seen as a massive threat to the X-Men the way Thanos is to the Avengers. He is historically the first mutant and one of the most powerful, and is connected to many major X-Men comics. Fans were eager to see the character in live-action, but his appearance in X-Men: Apocalypse left many disappointed with everything from the character's appearance to how quickly he was defeated. With the X-Men now set to join the MCU, the character of Apocalypse is one that needs a second go around for a proper depiction.
The character could easily be brought into the MCU, as many of the character's comic book lore is already established in the MCU. He has connections to The Celestials (established in Eternals) and to the Egyptian pharaoh Rama-Tut who is one of the incarnations of Kang the Conqueror who was teased in Loki and will make his first full appearance in Ant-Man and the Wasp: Quantumania. Moon Knight (which interestingly stars Oscar Isaac, who played Apocalypse in the Fox X-Men movies) has deep connections to Egyptian mythology, so there is room to build the character connections there as well.
4 Emma Frost
Emma Frost has acted as both an enemy to the X-Men and one of the team's most valuable members. The character is one of the most complex characters in the franchise and has a passionate fanbase, yet her live-action film appearances have left her fans wanting more.
The character appeared twice in the Fox films, first as a teenager in X-Men Origins: Wolverine and again in X-Men: First Class as a member of the Hellfire Club, but was killed off before the start of X-Men: Days of Future Past, meaning she didn't get quite enough time to develop as a character. In the MCU, Emma Frost could become the franchise's new Loki, one that walks the line between hero and villain.
3 Gambit
Introduced in the 1990s, Gambit gained a considerable fanbase due to his appearance in the beloved X-Men: The Animated Series. During the original trilogy, the filmmakers tried to work the character in as a cameo in X2: X-Men United and more fully in X-Men: The Last Stand, but the character was cut. He finally made an appearance in the much-hated X-Men Origins: Wolverine. Fox originally planned for the character to have a spin-off film starring Channing Tatum, but numerous production delays and changing directors meant the film never got made before Disney's acquisition of 20th Century Fox and the X-Men franchise ended. With the mutants set to return to the MCU, Disney could get Tatum to finally play the raging Cajun in the MCU.
2 Cyclops
One of the original X-Men members, Cyclops is one of the most iconic X-Men, having been a member in many incarnations of the team, where he is often the leader. Despite the good casting of James Marsden in the original trilogy, the character is sidelined for Wolverine and his role gets smaller in each subsequent film to where he is killed off early in X-Men: The Last Stand. The character returned to the franchise with Tye Sheridan playing a younger version of the character in X-Men: Apocalypse and X-Men: Dark Phoenix, but the actor never quite got the screen time or focus to really develop Cyclops.
While it is unclear what lineup the MCU X-Men will take, it is safe to assume Cyclops will be one of the members and the MCU has a chance to truly make him one of the core members and show why the character has endured for so long as a long term teammate.
1 Angel
No major X-Men character probably got a worse treatment in the Fox films than Angel. One of the original members of the team in the comics, the character was finally introduced in X-Men: The Last Stand. Yet despite a major push in the marketing, the character added up to a glorified cameo and didn't even suit up in an X-Men costume to fight alongside the team in the climax, despite the film's posters showing the character in uniform. He was not brought back for X-Men: Days of Future Past and was featured in X-Men: Apocalypse, but was relegated to a henchman and was quickly killed off.
With two iconic depictions, as both Angel and the more tragic Archangel, the character could benefit from the long-term storytelling potential of the MCU that was often lost in his previous film incarnations. While it is unlikely Angel is a high-priority character for the MCU, whatever the franchise does with him will likely be more substantial than how Fox treated the character.