First launched in "Uncanny X-Men" in 1963, the X-Men are some of the most powerful superheroes in comic book history, so their enemies have to be even more powerful. They don't tackle purse snatchers and bank robbers, but rather cosmic beings and mutants trying to destroy the universe.

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Since the first issue, the X-Men have gone up against a wide variety of supervillains that possess jaw-dropping levels of power, working for or against mutantkind, and some are even capable of altering time and space itself. Some of the X-Men's villains have been former allies, while others have been evil since the dawn of humanity. With a new X-Men movie set to begin production in the summer of 2017, we figure now is a good time for CBR to run down the 15 most powerful X-Men villains.

15 Juggernaut

First appearing in "X-Men" #12 in 1965, Juggernaut quite simply can't be stopped. The half-brother of Professor Charles Xavier, Marko stumbled into a cave and unearthed the mystical Crimson Gem of Cyttorak that transformed him into the Juggernaut.

Once Juggernaut starts moving, no force on Earth can stop him. His body generates a force field that makes him indestructible, resistant to heat, cold, pressure and anything else thrown at him. He doesn't need to eat or sleep or even breathe. He also has enormous physical strength, capable of smashing through any barrier. His only weakness is to psychic attack, which is why he wears a helmet resistant to all psychic powers, so the first rule of fighting him is always the same: take off his helmet. Juggernaut is one of the most persistent enemies of the X-Men, and has fought them for decades to prove himself better than his brother.

14 Mister Sinister

Mister Sinister has been around for decades, even working with the Nazis on eugenics experiments during World War II. In 1987's "Uncanny X-Men" #221, Mister Sinister sent the Marauders to slaughter the underground community of mutant outcasts, the Morlocks. Later, the X-Men discovered Sinister had been manipulating Cyclops since he was a child in order to make him conceive Nathan Summers, who eventually became the time-traveling mutant Cable. It was later revealed that Mister Sinister was a scientist from the 19th century who was so obsessed with evolution that he made a pact with the mutant Apocalypse to become immortal.

Sinister has a vast power set including telepathy, the ability to shape shift and regenerate, and project energy, but his greatest asset is his mind, which has constantly been set to the task of pursuing genetic research, and has allowed him to create clones to project his mind into after his own physical death. He's a ruthless and deadly villain who plans decades in advance, and has the resources to manipulate the world.

13 Krakoa the Living Island

One of the physically largest of the X-Men's enemies is Krakoa, who made its first appearance in "Giant Size X-Men" #1 (1975) when Xavier and Cyclops assembled a new group to find his original team, which had been lost on a remote island while looking for a powerful mutant. The new team (which included Wolverine, Storm and Colossus) traveled to the island of Krakoa, where they discovered the island itself was the mutant. Nuclear testing had fused all the lifeforms on it into a hive mind that attracted the X-Men to feed on them. Krakoa could use the animals and even the rocks against them.

Krakoa would be higher on this list if weren't for 2006's "X-Men: Deadly Genesis." There, Krakoa was retconned to not be a living island at all, but a deception to hide the existence of a lost team of X-Men (made prior to the one including Wolverine) whom Xavier thought had all been killed while trying to rescue Cyclops' teammates.

12 The Living Monolith

In "X-Men" #54 (1969), the X-Men first fought the Living Pharaoh, a professor of Egyptology who believed the ancient gods of Egypt were actually mutants. His theories led him to discover he himself was a mutant with the power to shoot beams of concussive force. He was taken in by the Cult of the Living Pharaoh that worshiped the ancient Egyptian gods, and became the cult's leader, not knowing they secretly worked for the mutant tyrant Apocalypse. Apocalypse used Mister Sinister to mix the Living Pharaoh's DNA with Havoc to make him more powerful, but the Living Pharaoh didn't stop there. Through experiments on Havoc, he drew even more energy to become the Living Monolith.

Over the years, he's fought the X-Men to try to increase his powers, absorbing more and more cosmic energy until he grew so large that Thor had to throw him into space, where he became a living planet in "Marvel Graphic Novel" #17. He eventually was recovered by Apocalypse who used the Living Monolith to absorb energy during the "Twelve" story arc. With his energy drained, he became the new Juggernaut, still wreaking havoc.

11 Master Mold

First appearing in "X-Men" #15 (1965), Master Mold was created by Bolivar Trask, a scientist who saw the emerging mutant race as a threat to humanity. Trask created the powerful Sentinels, powerhouse robots that can fly and adapt to a variety of mutant powers, dedicated to hunting down mutants. Master Mold is the lead Sentinel who can manufacture and design other Sentinels. Every time the X-Men think they've destroyed it, it's survived and rebuilt itself.

Given enough time and resources, Master Mold can create an army of robot Sentinels that can overwhelm almost any mutant. The Sentinels it creates can be as large as skyscrapers or small enough to penetrate human cells. Also, since it's also a Sentinel itself, Master Mold can detect and hunt down mutants with surgical skill. Master Mold is also artificially intelligent with its own agenda of enslaving humanity to protect it from the mutant menace.

10 The Brood Empress

If the Xenomorphs from the Aliens movie series were supervillains, they would be the Brood. The Brood first appeared in "Uncanny X-Men" #155 (1982), and made a huge impression. They're ferocious in battle with huge fangs, wings and tails that can either paralyze or kill by injecting poisonous venom into their victims. The worst part of the Brood is their need to infect other species with their eggs in order to reproduce. Once infected, the hosts are taken over and transformed into a Brood themselves.

All Brood are led telepathically by the Brood Empress, who can't control them directly, but can send commands. The Brood Empress is not only ruthless in her quest to expand her race, but also sadistic, revelling in the terror her minions bring. She has led the Brood on multiple invasions of Earth against the X-Men, trying to add the powerful mutants to her hive. With enough soldiers at her command, she's almost unstoppable.

9 Proteus

First appearing in "Uncanny X-Men" #125 (1979), Proteus is the mutant child of scientist Moira MacTaggert, who was forced to keep him imprisoned at her Mutant Research Center because of his constant desire for energy. During a fight between Magneto and the X-Men, his original body burned out and he escaped by becoming a being of pure psychic energy who jumped into a new person. From then on, he needed host bodies to contain himself. He renamed himself Proteus and goes from one body to another, using them up until his power burns them out.

Proteus has the power to alter reality itself, changing object sand space to become whatever he wants. He can also jump into other human bodies to access their memories and abilities (in the case of mutants like Rogue), and even developed the ability to possess multiple bodies at once at the price of reduced power. Knowing his destructive power, Proteus has been dispersed multiple times, but always returns.

8 Nimrod

In the alternate future of 1981's "Days of Future Past," Sentinels have taken over the world and rounded up mutants in concentration camps. The most advanced of the Sentinels was Nimrod who was programmed to exterminate all mutant life. As a robot capable of changing size and shape to pass as a human being, Nimrod can become undetectable and also has the ability to repair himself, making himself virtually indestructible. When Rachel Summers traveled from his future to the present day, Nimrod followed.

Nimrod could have destroyed all mutants in the present if his programming hadn't changed from exterminating all mutants to exterminating mutants that threatened humans, which came to be the X-Men. Later, Master Mold took control of it, becoming even more powerful in the process. Fortunately, Nimrod came to rebel against its programming and convinced Master Mold it was a mutant itself, and self-destructed. Nimrod and Master Mold later merged to become Bastion.

7 Stryfe

Making his first full appearance in "New Mutants" #86 (1990), Stryfe is a clone of the psychic Cable that was taken and raised by Apocalypse to become Stryfe. As an adult, Stryfe rebelled from Apocalypse and became a mortal enemy of Cable and the X-Men, dedicated to destroying his clone brother.

Stryfe has all the psychic power of Cable, which included the power to read and control minds, telekinetically move massive objects and create psychic illusions. The difference is that Stryfe was cured of Cable's techno-organic virus, so he can do even more than Cable can. In addition, Stryfe has modified himself to increase his strength and durability, making him even stronger and more dangerous. He also lacks any moral code, willing to do anything to seize power. In his most recent appearance, Stryfe was turned into pure consciousness and dispersed, but since we're talking about comics, he could still return.

6 The Shadow King

Little is known about the true nature of the Shadow King, an ethereal being that has existed since the dawn of humanity who first appeared in "X-Men" #117 (1979). It feeds on fear and hatred, and passes from one human host to another. Xavier first encountered the Shadow King in Cairo, where it had possessed the body of a mutant named Amahl Fahrouk. When the two connected telepathically, Xavier was so shaken by his power that it inspired him to create the X-Men to fight threats like him. Since then, the Shadow King has fought against the X-Men multiple times, possessing various members like Psylocke.

The Shadow King has enormous psychic power, on par with Professor Xavier himself. He can control people's minds and bodies, and can escape to the astral plane, making him immortal. If it weren't for the power of telepaths such as Jean Grey, Psylocke and Professor X, the Shadow King would already control the world.

5 Cassandra Nova

Before Charles Xavier was born, a mystic being known as a mummudrai copied his DNA to become his evil twin sister. We're talking super-evil, so evil that Xavier tried to strangle her to death in the womb with her umbilical cord. That twin sister survived and became an evil woman with enormous psychic power named Cassandra Nova. Making her first appearance in "New X-Men" #114 (2001), Nova created an army that wiped out most of the population of the mutant nation of Genosha. Though she was forced out of a physical body, she continued to cause chaos among the X-Men in her attempts to destroy them and the mutant population of Earth.

Nova has all of Xavier's powers, including telepathy, astral projection, telekinesis and the ability to mimic anyone right down to their DNA. What she doesn't have is a sense of right and wrong. She'll happily destroy the universe if it means getting her revenge on Xavier.

4 Magneto

When it comes to mutants, only a handful can really qualify as the most powerful, known as Omega Level. Magneto is definitely one of those mutants. First appearing in 1963’s “Uncanny X-Men” #1, Magneto was once Max Eisenhardt, a man imprisoned with his family in a Nazi concentration camp where the horrors he saw at the hands of the Nazis convinced him of how dangerous humans can be. When he discovered his mutant power to control metal, he became Magneto and dedicated himself to defending mutantkind from humanity.

Magneto is one of the most powerful mutants on Earth. With his ability, he can disassemble and reassemble all things metal, turning weapons into scrap and scrap into weapons. He once even ripped the seemingly indestructible adamantium metal out of Wolverine's bones, and has taken control of nuclear missiles to try to launch World War III. His cause is just, but his means aren't and his power is beyond imagination, a combination that often makes him one of the X-Men's biggest recurring threats.

3 Apocalypse

He made his full debut in "X-Factor" #6 (1986), and quickly became one of the greatest threats in comic book history. As the first known mutant, Apocalypse used his incredible power to seize control of ancient Egypt. Using futuristic technology, Apocalypse lived for thousands of years, obsessed with the concept of survival of the fittest. Coming to believe humanity needs to be tested, Apocalypse unleashed his power to plunge the world into war. Each time, he's taken on four mutants as his Horsemen, including the mutant Angel and even the Hulk.

It's hard to say what the exact strength of Apocalypse's powers are, because there hasn't been a limit found. He has complete control of his molecular structure, allowing him to change shape and density at will, teleport and even fly. He's a master of genetics, and will even occasionally switch bodies if needed. Of all the X-Men villains who want to destroy the world, Apocalypse has come the closest to succeeding.

2 The Phoenix Force

For a long time in the comics, no one knew about the Phoenix Force. They only knew about Phoenix, the reborn and more powerful identity of Jean Grey. While trying to stop a crashing spaceship, she came back as a more powerful being calling herself Phoenix. At first, Phoenix thought she was Jean Grey, but grew more and more powerful until she consumed a planet, killing billions. She finally killed herself, but the X-Men later discovered she wasn't Jean Grey at all. The real Jean Grey had been preserved in stasis, and the one who had died had been the embodiment of her power known as the Phoenix Force.

The Phoenix Force is a manifestation of psychic energy born from the universe itself, and later inhabited other bodies like Rachel Summers. The Phoenix Force is pure psychic power capable of creating beams of energy powerful enough to defeat a weakened Galactus. It can even reach through time and change history. There are no known limits to the power of the Phoenix Force.

1 Onslaught

Professor Xavier and Magneto have always been ideological opposites, sometimes enemies and sometimes friends. One thing that's really brought them together is the supervillain Onslaught, because he's literally a combination of the two. During a battle, Charles Xavier entered Magneto's mind to put him into a coma and, in the process, part of Magneto's mind entered Xavier's. The negative emotions of both combined to become a psychic entity known as Onslaught.

In "X-Men" #53 (1996), Onslaught took control of Xavier's body and began a campaign to wipe out humanity. Onslaught has taken control of an army of Sentinels and even the Hulk to achieve his goals. Onslaught eventually came to possess all the power of Professor X, Magneto, Franklin Richards and X-Man, all of whom were extremely powerful to begin with. With his almost limitless psychic powers, Onslaught almost destroyed the world until the X-Men, Avengers and other Marvel heroes managed to disperse his consciousness.

Which do you think is the most powerful X-Men villain? Are there any you would have added to this list? Let us know in the comments!