When it comes to enemies, there are few groups in comics that have ones as cool as the X-Men. Not only are they some of the most powerful villains in comics, but also some of the most interesting, from the stereotypical villains who are out for themselves to more complex villains fighting against the discrimination of humanity by any means necessary. Speaking of human discrimination, society itself is often the X-Men's greatest foe, working against the mutant race any way they can.
With the X-Men soon coming to the MCU, there are many X-Men villains who are ready for their big-screen debut and could have amazing movies made about them.
10 Avalanche — With modern special effects being what they are, it would be a treat to see him using his earthquake-inducing powers against the X-Men
Avalanche isn't the kind of villain whom a whole movie can be built around but that doesn't mean he shouldn't be put into movies. Powerful villains always need lackeys, especially when fighting teams like the X-Men and Avalanche would be perfect for that. A longtime member of the Brotherhood of Evil Mutants, Avalanche's seismic powers make him a formidable foe.
With modern special effects being what they are, it would be a treat to see him using his earthquake-inducing powers against the X-Men, holding them back before they could get to the big bad.
9 Daken — Seeing a big-screen fight between Daken & Wolverine would be a lot of fun
Wolverine's estranged son, Daken quickly became one of the Canadian mutants greatest foes. Much like his father, he has a healing factor, super-senses, and claws, but he also has the ability to control his pheromones, making him irresistible to either sex. This would make him a great foil for the X-Men, as he could infiltrate the team, make them love him (literally), and strike from within.
Seeing a big-screen fight between Daken and Wolverine would be a lot of fun and the mutant could also be more than a match for many other members of the team. Plus, he can be used in future Wolverine movies later down the line.
8 Bastion — Bastion & the Prime Sentinels would be great adversaries for the X-Men on the big screen, highlighting humanity's discrimination against the mutants
The Sentinels have always been one of the dangerous threats to mutantkind but one of the most dangerous Sentinels of them all was Bastion. A Nimrod unit that went through the magical Siege Perilous, Bastion gained complete sentience and a new body, setting out to destroy mutants. Creating the nanite-based Prime Sentinels, he used the government based Operation: Zero Tolerance to strike at mutants after Onslaught's attack on New York.
While some changes would have to be made to Bastion's rather complicated origin, Bastion and the Prime Sentinels would be great adversaries for the X-Men on the big screen, highlighting humanity's discrimination against the mutants and making them wonder who they could trust as the Prime Sentinel sleeper agents awakened around them.
7 Onslaught — He could make a great big bad villain not just for the X-Men but for the MCU in general
One day, the X-Men are going to have to crossover with the MCU and while there are lots of stories that meeting can be based off, like Avengers Vs X-Men, it may be better to have the two teams meet as allies rather than enemies. With that in mind, it might be best to put the two teams against Onslaught.
Born from the evil of Magneto latching on Professor X when Xavier mindwiped the magnetic mutant, Onslaught would use his amazing powers to attack New York City and embroil all of the heroes of the Marvel Universe in the conflict. Onslaught could make a great big bad villain not just for the X-Men, but for the MCU in general.
6 Stryfe — Stryke can be introduced before or after Cable & would be a formidable foe for the X-Men
Since his debut in the '90s, Cable has been among the most popular mutants around. While he was known for his big guns, he also has vast telepathic and telekinetic abilities, most of which he uses to keep the techno-organic virus ravaging his body at bay. So, what if he didn't have the virus? How powerful would he be?
Stryfe answers that question. A clone of Cable created by Apocalypse, Stryfe brought together a group of evil mutants, the Mutant Liberation Front, to battle Cable's X-Force. Stryke can be introduced before or after Cable and would be a formidable foe for the X-Men.
5 Belasco — While fans are used to seeing the X-Men as superheroes, bringing Belasco in could show just how well the team works in fantasy settings
With the recent panning of The New Mutants, Marvel Studios might not be too keen to bring the team or its members back, but if they did, Magik would be a great character to pick. Explaining Magik's, well, magic would mean having to explain her time in Limbo, the realm of the demon known as Belasco.
While fans are used to seeing the X-Men as superheroes, bringing Belasco in could show just how well the team works in fantasy settings. Whether having the X-Men enter Limbo to rescue a young Illyana Rasputin and finding her transformed or having Belasco come after her, the lord of Limbo would be a great addition to the villains of the MCU.
4 Cassandra Nova — With her personal connection to the team, Cassandra Nova would be a perfect villain
The evil twin of Charles Xavier, Cassandra Nova, survived him trying to kill her in the womb to become one of the greatest enemies of mutantkind. Using Wild Sentinels to kill sixteen million mutants, she would take over her brother's body and attack the Shi'Ar Empire before coming back to Earth and almost killing all the mutants in one fell swoop.
She would attack the team several more times, using her vast telepathic powers and intellect. With her personal connection to the team, Cassandra Nova would be a perfect villain for them and one the likes of which moviegoers have never seen before.
3 The Shadow King — Seeing the X-Men have to go to the Astral Place to fight him would be amazing, putting the CG & special effects of Marvel Studios to great use
The Shadow King is one of the most powerful telepaths in the world. Familiar to fans of the show Legion, Amahl Farouk desires nothing more than the complete subjugation of every mind on Earth. While he's not a physical threat, his ability to control minds could make for an interesting movie, as the X-Men would never know who he was controlling or who they could trust.
Seeing the X-Men have to go to the Astral Place to fight him would be amazing, putting the CG and special effects of Marvel Studios to great use. A movie with Shadow King as a villain would be a different kind of X-Men movie and that's something the MCU needs — a way to break their formula.
2 Mojo — it's hard to deny he would be a great villain for an X-Men movie & a great visual as well
Mojo is the leader of Mojoworld, a world that is ruled by whoever has the highest ratings. Mojo's shows are violent spectacles and he often ensnares the X-Men in them. While he himself isn't much of a fighter, he has legions of minions on his side and his penchant for creating violent shows for the X-Men to survive would be quite a test for the team.
Of course, since Mojo is meant to be a swipe at network and film execs, he may be a bit of a hard sell for the bigwigs who he resembles. However, it's hard to deny he would be a great villain for an X-Men movie and a great visual as well.
1 Mister Sinister — Powerful, intelligent, & entertaining, Mister Sinister would make a great villain for an X-Men movie
Mister Sinister is the biggest X-Men villain to not get a big-screen debut during Fox's X-Men tenure. Teased in a post-credit scene of The Wolverine, fans were hoping to see him, but Fox took the moves a different way. The MCU could easily remedy this and Sinister would be perfect for an X-Men movie.
Whether by himself or with his henchmen, the Marauders, Mister Sinister has always been a grave threat to the X-Men, his obsession with genetics, and the genetics of Cyclops and Jean Grey, in particular, putting him at odds with the team.