With X-Men: Dark Phoenix due for release in February of 2019, it’s pretty obvious that the movie’s titular character will serve as its primary antagonist, despite the assumed presence of some as-of-yet undisclosed secondary villains. Beyond that however, the future of the villains in Fox’s ever-expanding X-Men franchise is completely open to speculation, with no apparent ‘big bad’ planned for the X-Men Universe in the same way Marvel Studios teased Thanos for so many years. With The New Mutants also set to release next year as well as movies based on Gambit, X-Force, Kitty Pryde, Multiple Man and X-23 in various stages of production, there’s a lot of room for new X-Men villains to steal the spotlight over the next few years -- but who exactly could Fox choose to fill those roles?

After all, the majority of the X-Men’s most iconic villains have already been featured heavily in the movies, from Magneto, Sabretooth, Mystique and Lady Deathstrike to William Stryker, Sebastian Shaw, Juggernaut and Apocalypse. With that said, the X-Men have over 50 years’ worth of villains to draw from going forward, meaning there’s still plenty of characters the movies could use. From widely-recognizable fan favorite characters to more underrated, obscure ones, the franchise could go in several different directions from here, especially since the Universe is continuing to expand in scope with lesser known teams and characters getting their own movies in the near future. With that in mind, CBR is here to take a look at 20 X-Men villains who could serve as the next big threat in Fox’s X-Men franchise.

20 ONSLAUGHT

Consistently ranked as one of the most powerful entities in all of Marvel Comics, Onslaught was born from the fusion of Magneto and Professor X’s minds during a particularly heated battle between the pair. With Magneto’s rage and obsession with mutant supremacy blending with Charles’ disappointment in the current state of human-mutant relations, Onslaught became fixated on destroying all of humanity.

With a set of godlike superpowers, Onslaught has all the abilities of Magneto and Professor X -- and even Nate Grey and Franklin Richards -- although to a much higher degree. Boasting unmatched, cosmic-level telepathy and telekinesis, Onslaught also has vast reality warping and energy projection abilities, making him perhaps the closest thing to omnipotent that a superpowered being can get.

19 BASTION

First appearing as an enigmatic politician in charge of the anti-mutant government group known as Operation: Zero Tolerance, Bastion’s true nature is later revealed to be anything but human. A fusion of the two Sentinel beings, Nimrod and Master Mold, Bastion assumes a more humanoid form than his predecessors, initially having his memory wiped until coming into contact with an inactive Master Mold unit.

Possessing the majority of Nimrod and Master Mold’s powers, Bastion is incredibly fast and strong, with an artificial healing factor and near-immortality that make him a complete powerhouse. In fact, Bastion even managed to end Nightcrawler during "X-Men: Second Coming", in which the villain was hellbent on destroying the mutant messiah Hope Summers.

18 STRYFE

Secretly planned to serve as the next host body for Apocalypse, Stryfe is an evil clone of the omega-level mutant Cable, raised by En Sabah Nur from birth. Naturally, his supervillainous upbringing gave him a predisposition for evil early in life, but his rage only fully exploded after learning of his status as a clone, declaring war on the X-Men as a result.

With powers practically identical to those of Cable, Stryfe is not limited by the techno-organic virus that infects his genetic twin, making him one of the deadliest foes the X-Men have ever faced. Boasting almost unmatched psionic abilities, Stryfe has immense telepathic and telekinetic abilities and is also cybernetically enhanced, granting him superhuman strength, with his armor providing near-invulnerability.

17 CASSANDRA NOVA

Cassandra Nova prepares to attack

Another interesting villain created by Grant Morrison for New X-Men #114, Cassandra Nova is as unique and peculiar a character as you might expect from the writer. An incorporeal life form birthed on the astral plane, the evil Cassandra latched herself onto an unborn Professor X, using his DNA to create a body for herself. While she was ultimately stillborn however, she survived as a mass of cells and eventually formed a new body.

The ideological polar-opposite of Charles Xavier, Cassandra has vast psionic abilities, and can possess others as well as exist without a body. A near-unstoppable force of nature, Cassandra Nova has one of the largest body counts of any villain in the Marvel Universe, decimating the population of Genosha which includes countless millions.

16 ARCADE

Arcade in Avengers Arena

Created by Chris Claremont and John Byrne for 1978’s Marvel Team-Up Vol. 1 #65, Arcade is one of the quirkiest villains in the X-Men’s rogues gallery -- sometimes depicted as a campy, comedic character and other times portrayed as a more legitimately intimidating presence.

An evil genius and assassin, Arcade ensnares his victims in a twisted funhouse known as “Murderworld”, which he fills with lethal traps and games. While his plans fail most of the time however, Arcade does occasionally manage to rack up a significant body count -- particularly in Avengers Arena, in which he successfully forces several young heroes to fight for their lives.

15 MASTER MOLD

Created by the nefarious Dr. Bolivar Trask -- a character best known for his creation of the deadly Sentinels -- Master Mold was built as a portable device for producing the mutant-hunting robots en masse. Colossal in size with a more humanoid appearance than his mechanical kin, Master Mold is also far more powerful than your average Sentinel.

As well as having the ability to scan mutants and the typical super-strength, flight and energy projection associated with other Sentinels – albeit to a much more potent degree -- Master Mold can also absorb metal into his own body, boosting his strength and enabling him to change his size and shape at will.

14 EXODUS

Born in the 12th Century with the name Bennet Du Paris, Exodus is one of the earliest, and most powerful, mutants on record, fighting alongside the Black Knight in the Crusades and later becoming an ally of Magneto in his fight for mutant supremacy. Clashing with the X-Men multiple times since his debut in 1993’s X-Factor #92, Exodus is one of the most powerful mutants in existence despite his relative obscurity as a character.

One of the most powerful psionic beings in the Marvel Universe, Exodus has tremendous telepathic and telekinetic ability, his abilities rivalling those of even Emma Frost, Jean Grey and Professor X. With superhuman strength, durability and healing abilities, Exodus is near-invulnerable, and can even raise the dead on occasion.

13 JOHN SUBLIME

Born from the minds of writer Grant Morrison and artist Leinil Francis Yu, Sublime made his first appearance in 2001’s New X-Men Annual Vol. 1. As you’d expect from Morrison, Sublime is one of the weirdest, most interesting modern X-Men villains in recent memory thanks to his status as a sentient bacterium.

His unique physiology allows him to infect and possess countless other lifeforms -- with the exception of certain mutants, who he has distinct hatred for -- with Sublime even proving himself capable of large scale mind control as well as genetic and cellular manipulation. In fact, Sublime has a much deeper history with the Marvel Universe than most people realize, secretly responsible for the creation of the Super Soldier programs that birthed the likes of Wolverine, Captain America, Fantomex and Deadpool.

12 NIMROD

Nimrod X-Men

While a variation of Nimrod appeared in 2014’s X-Men: Days of Future Past in the form of multiple Nimrod Sentinels, the comic book version of Nimrod is much more of a well-defined character in his own right, appearing as a singular villain of the X-Men as opposed to an army of anonymous robots.

Following Rachel Grey from the “Days of Future Past” timeline to Earth-616, Nimrod is an incredibly powerful form of Sentinel capable of destruction on a massive scale, even able to take on the Juggernaut in hand-to-hand combat. With the powers of energy projection, teleportation and a robotic form of healing factor, Nimrod can also shapeshift at will, allowing him to pose as a human to track down his mutant prey.

11 SAURON

marvel-sauron

Visiting the Savage Land alongside his adventurous father during his teenage years, Karl Lykos was bitten by a mutated pterodactyl during the trip, with the young scientist later discovering the ability to drain the life force of other beings. Becoming addicted to this life force, Karl is eventually transformed into the human-pteranodon hybrid Sauron after attempting to feed on Havok’s energy, turning him into a vicious villain -- coming to blows with the X-Men on several occasions as a result.

Able to fly at great speeds, Sauron also possesses super-strength and stamina, can hypnotize others to do his bidding, and even later gains the ability to project energy blasts from his hands and breathe fire.

10 VULCAN

The long-lost brother of Cyclops and Havok, Vulcan was briefly a member of the X-Men after his existence was discovered by the team, but eventually garnered a bitter hatred for his former colleagues after being left for dead on Krakoa. Vastly more powerful than his brothers, Vulcan is one of the most dangerous mutants in the Universe, even able to drain Adam Warlock of his powers in one of their confrontations.

Boasting the ability to psionically absorb and control energies from the entire electromagnetic spectrum, Vulcan can use this ability to perform a whole host of impressive feats, including generation of electricity, heat blasts, force fields and concussive force, just to name a few.

9 PROTEUS

Proteus - omega level mutant in Marvel Comics

The son of scientist Moira MacTaggert and abusive politician Joseph MacTaggert, Kevin MacTaggert’s early life was filled with trauma -- a fact only worsened by his burgeoning mutant powers, which were deemed incredibly dangerous by his mother. Placed in a holding cell for the good of himself and others, Kevin grew disillusioned with life, eventually escaping and wreaking havoc, bringing him into conflict with the X-Men.

With his mutant power allowing him to control the fabric of reality itself, Proteus can rewrite the laws of physics and transmute matter on a huge scale. Perhaps his most disturbing power however is the ability to possess the bodies of others, absorbing their energy before leaving them comatose, with Proteus able to exist in a state of pure energy, making him nigh on indestructible.

8 COUNT NEFARIA

First appearing in 1965’s The Avengers #13 -- later becoming an enemy of the X-Men, too -- Luchino Nefaria is a privileged aristocrat and member of the Maggia residing in Italy, given superpowers through a HYDRA experiment that grant him the strength of Luke Cage, the energy projection of the Living Laser and the speed of Whirlwind, although these powers are said to have been ‘amplified a hundredfold.’

As a result, Count Nefaria is one of the most physically powerful characters in the entire Marvel Universe, able to take on some of Marvel’s strongest characters, even brushing off blows from Mjolnir with ease.

7 MASTERMIND

Mastermind standing behind Jean Grey

Amongst the earliest villains the X-Men ever faced having been introduced in 1964’s The X-Men #4, Mastermind remains one of the team’s most formidable foes to this day. Serving as a key member of both the Hellfire Club and the Brotherhood of Evil Mutants, Mastermind is just as dangerous operating alone as he is in a team.

A mutant with the ability to cast powerful illusions and alter the memories of his enemies, Mastermind hardly has the most versatile skillset in the Marvel Universe -- even his telepathic powers pale in comparison to the likes of Jean Grey and Professor X -- but his uncanny ability to manipulate and concoct convoluted schemes are second to none, making him one of the X-Men’s most psychologically damaging villains in existence.

6 PHALANX

Created from the remains of the cybernetic technarch Warlock by a group of anti-mutant scientists, the Phalanx are one of the deadliest species known to mutantkind. Operating under a complex form of hive mind, the Phalanx are able to infect their victims with the transmode virus – a techno-organic virus that absorbs its host into their collective consciousness, effectively turning them into a member of the Phalanx themselves.

With their ultimate goal being the complete assimilation of mutantkind into their ranks, the Phalanx can even shapeshift into human form, enabling them to single out and infect their victims with much greater ease.

5 DARK BEAST

Marvel Comics X-Men Darkbeast in his lab.

One of the few characters from the ‘Age of Apocalypse’ timeline deemed interesting enough to be brought into Marvel’s mainstream continuity, the alternate timeline Hank McCoy is far more than just an evil version of the X-Men’s beloved Beast. Although he may resemble his Earth-616 counterpart, Dark Beast couldn’t be more of a far cry from the original Hank McCoy.

Using his genius to conduct brutal experiments and cause hell for the X-Men, Dark Beast is cruel and calculating, showing no qualms with the brutal murder of innocents for no apparent reason. Though he’s been forced to engage in an uneasy alliance with the X-Men on occasion, Dark Beast essentially serves as Beast’s shadow self -- showing what he could become if he were to lose touch with his humanity.

4 MOJO

Ruling over an alternate dimension known as the Mojoverse, the aptly-named Mojo is an alien slaver infamous for forcing his dimension’s superpowered residents into vicious gladiatorial combat, which he televises for his subjects. Possessing a variety of magical abilities, Mojo’s power increases the more he’s ‘worshipped’, giving him an obsession with garnering high ratings for his twisted entertainment. Additionally, Mojo appears to radiate an ‘anti-life field’ that ages and slowly finishes off nearby organisms.

Created as a tongue-in-cheek commentary on the excess and corruption of movie and television executives, Mojo seems like a perfect fit for a more humorous X-Men movie -- perhaps even the upcoming X-Force movie.

3 KANG THE CONQUEROR

A time-travelling villain hellbent on subjugating the universe, Kang the Conqueror’s past remains enigmatic to this day, despite first appearing way back in 1963’s Fantastic Four #19. A tactical genius wielding a series of highly advanced future weapons, Kang the Conqueror is a true force to be reckoned with despite having no inherent superpowers.

Sure, Kang primarily appears as an antagonist of the Avengers, but he has also come into conflict with the X-Men in the past, particularly with the Avengers Unity Squad -- a team consisting of a combination of X-Men and Avengers. Should the X-Men finally join the MCU following Disney’s purchase of Fox, Kang would actually be the perfect villain to galvanize the two teams, finally bringing the X-Men into the fold after all these years.

2 OMEGA RED

Omega Red by Jim Lee

Introduced as a Russian criminal named Arkady Gregorivich Rossovich, Omega Red got his powers after being subjected to a brutal series of Super Soldier experiments by the KGB. Granted superhuman strength, speed, agility, reflexes and durability, Omega Red also has a set of indestructible carbonadium tentacles implanted in his arms, allowing him to unleash vicious attacks on his enemies.

Also capable of releasing "spores” that weaken and eventually finish off his enemies, Omega Red can even drain his victims of their life force -- an act he’s forced to commit to halt the carbonadium poisoning coursing through his veins. Though he’s primarily an enemy of Wolverine, there’s no reason Omega Red can’t make his way into Fox’s X-Men franchise as an enemy of the core team, or perhaps even X-23.

1 MR. SINISTER

Mr Sinister

Amongst the most recognizable X-Men villains in existence, Mr. Sinister has been teased several times in Fox’s X-Men movies but has yet to make a full appearance, making him a shoo-in to serve as the franchise’s next big bad. Originally a brilliant 19th Century biologist named Nathaniel Essex, Mr. Sinister was born after allying himself with Apocalypse, who changed his physiology and granted him an incredible set of superpowers.

In addition to his pre-existing genius-level intellect, Essex gained the ability to alter his own body at a molecular level, giving him shapeshifting abilities and a healing factor,  as well as telepathy, telekinesis, teleportation, energy projection and an immunity to the aging process.