Marvel Studios has the opportunity to introduce iconic X-Men villains, such as the Shadow King, Mister Sinister, and Arcade, that were neglected in Fox’s franchise.
The MCU’s future could feature terrifying enemies like Cassandra Nova, Danger, Onslaught, Proteus, Mastermind, Omega Red, and the Friends of Humanity.
The inclusion of these powerful and memorable villains would add depth and excitement to the X-Men’s storyline in the Marvel Cinematic Universe.

Several iconic X-Men villains from Marvel Comics in Fox’s superhero franchise, so Marvel Studios has the chance to debut some of these terrifying enemies when the mutant team is introduced to the MCU. Before Marvel Studios acquired the film rights to mutants and the X-Men in 2019, 20th Century Fox built a massive film franchise featuring the mutant characters from Marvel Comics. Although Fox’s X-Men film series spanned thirteen films and two TV shows between 2000’s X-Men to 2020’s The New Mutants, many heroes and villains associated with the team in Marvel Comics went unused, but some of these iconic characters could appear in the MCU’s future.

Disney acquired 20th Century Fox’s properties in 2019, leading to teases of mutants and the Fantastic Four in various MCU projects, including Ms. Marvel and Doctor Strange in the Multiverse of Madness. 2024’s Deadpool 3 will take this a step further, as at least some of the film’s storyline is expected to take place in Fox’s X-Men universe ahead of the introduction of the MCU’s official X-Men team. While the debut of mutant heroes in the MCU is very exciting, Marvel Studios also has the opportunity to give attention to villains associated with the X-Men that were neglected in Fox’s franchise, including these ten powerful enemies from Marvel Comics.

10 Shadow King

Amahl Farouk, a.k.a. the Shadow King, is one of the X-Men’s most memorable and prevailing enemies, debuting in Marvel Comics’ 1979 story, Uncanny X-Men #117. The Shadow King was the primary antagonist of FX’s Legion, an X-Men-adjacent series, where the entity was portrayed by Aubrey Plaza and Navid Negahban, but the character never made an appearance on the big screen despite being depicted as Professor X’s nemesis. Farouk claims to be a manifestation of the darkness of human consciousness, and his formidable abilities make him a terrifying foe to the X-Men. The Shadow King is an incredibly cinematic villain who deserves a great deal of attention in the MCU.

9 Mister Sinister

Mister Sinister is one of the X-Men’s most iconic villains in Marvel Comics, plaguing the team and mutantkind for decades since his debut in 1987’s The Uncanny X-Men #221. Originally Nathaniel Essex, a 19th-century genetic engineer, Sinister became fascinated with mutants and their physiology and conducted traumatic experiments on them for several years. After teaming up with Apocalypse, Essex was genetically transformed into an ageless, telekinetic being who would go on to become one of the X-Men’s most infamous foes. Despite being repeatedly teased in Fox’s X-Men franchise, Essex never made an appearance, so Mister Sinister’s potential debut in the MCU would finally give him the focus he needs.

8 Arcade

The combination of an evil genius and a skilled hitman, Arcade has wreaked havoc on many Marvel heroes since his introduction in 1978’s Marvel Team-Up, Vol. 1 #65, including Spider-Man and Captain Britain. His most prominent foes, however, have been the X-Men, X-Factor, and X-Force teams, using various elaborate traps and illusions to battle these heroes. In his seminal storyline, 2012’s Avengers Arena, Arcade kidnaped 16 superpowered teams and forced them to fight to the death in an updated version of his Murderworld scheme, which could be the perfect storyline to adapt into a future MCU project, putting this manipulative supervillain front-and-center.

7 Cassandra Nova

Cassandra Nova is a more recent villain introduced in Marvel Comics, debuting in 2001’s New X-Men #114, though is perhaps one of the team’s most petrifying enemies. Cassandra is a Mummudrai, a parasitic, bodiless life form born on the Astral Plane. After becoming entangled with Professor X, the Mummudrai adopted some of his psychic abilities, which allowed her to create a body and become the embodiment of Xavier’s darkness. After emerging, Cassandra commanded Sentinels to commit genocide on 16 million mutants living on the island of Genosha. Cassandra has been rumored to be appearing in Marvel Studios’ upcoming Deadpool 3, perhaps committing genocide on the mutants of Fox’s X-Men universe.

6 Danger

The Danger Room is the X-Men’s training facility inside the X-Mansion, but in 2005’s Astonishing X-Men, Vol. 3 #8, the Danger Room gained self-awareness and uses an old Sentinel body to wreak havoc on the X-Men. Danger later takes the form of a woman and becomes an ally to the X-Men, particularly Gambit, and both characters were originally rumored to be making appearances in Deadpool 3. It seems Danger’s Deadpool 3 appearance has been debunked, but since the Danger Room was seen on various occasions in Fox’s franchise, it’s possible this villain could still make an appearance and could be an important part of the MCU’s X-Men story.

5 Onslaught

Onslaught is a sentient psionic being created from the dark corners of Professor X and Magneto’s consciousnesses, formed after their minds became entangled during battle. Onslaught remained dormant in Xavier’s mind for a while, manipulating the leader of the X-Men to work against his team before manifesting its own body. To bring him down, the X-Men banded together with the Avengers and the Fantastic Four, culminating in the apparent deaths of several high-profile heroes. If Professor X and Magneto appear in Deadpool 3, Onslaught could be the perfect villain to bring into live-action, as he’d bring about the perfect farewell to many of Fox’s previous mutant heroes.

4 Proteus

Also known as Mutant X, Proteus is one of the strongest and deadliest mutant villains to ever appear in Marvel Comics, as he has incredible abilities, including reality warping and body possession. Proteus, a.k.a. Kevin MacTaggart, was the son of Moira MacTaggart and her abusive husband, Kevin, and was tragically the product of rape. When his abilities began to manifest, the danger he presented prompted his mother to confine him, but he escaped after a battle with Magneto and the X-Men. Moira MacTaggart was seen in Fox’s X-Men franchise, but Kevin never got a mention, so Marvel Studios could finally introduce this powerful yet damaged character to the MCU.

3 Mastermind

Mastermind is a mutant with the ability to create complex telepathic illusions, causing others to see, hear, or feel things that simply don’t exist. This manipulation makes him a terrifying threat to the X-Men, and the fact that he is a founding member of the Brotherhood of Evil Mutants could set him up as an important character in the MCU’s future. Mastermind and his successors repeatedly clash with the X-Men, and he plays a pivotal role in Marvel Comics’ Dark Phoenix Saga. Fox attempted this iconic storyline twice, and both attempts were poorly received, so Marvel Studios could finally do justice to this storyline in the MCU.

2 Omega Red

Arkady Gregorivich Rossovich, a.k.a. Omega Red, was a prominent Russian serial killer who was experimented on to become a super soldier similar to Captain America. As part of his enhancements, Omega Red was fitted with retractable carbonadium (Russia’s attempt at creating adamantium) tentacles in his arms, akin to Wolverine’s claws, which allowed him to drain the life force from his victims. With Marvel Studios delving into Russia’s superpowered history in Phase 4, particularly with the debut of the Red Guardian, it may be the perfect time to introduce Omega Red to the MCU, which could occur in Deadpool 3, as Wade Wilson had dealings with Omega Red in Marvel Comics.

1 Friends Of Humanity

Marvel Comics’ Friends of Humanity was a pro-human mutant-hate group founded by Graydon Creed and became a persistent thorn in the side of the X-Men. One of the key elements of mutants’ stories in Marvel Comics is the discrimination and racism they face, so this will be an important narrative to explore in the MCU, and the Friends of Humanity would be the perfect representation of this. Creed was eventually assassinated by Mystique, but the group continued to grow, and even inspire other mutant-hate groups. Marvel Studios needs to be sensitive in adapting these mutant storylines in the MCU, as they’re essential to delivering an impactful and effective X-Men story.

Key Release Dates

The Marvels

Deadpool 3

Captain America: Brave New World

Marvel’s Thunderbolts

Blade (2025)

Marvel’s Fantastic Four

Avengers: The Kang Dynasty

Avengers: Secret Wars

 The MCU can debut many unused X-Men villains.  Read More