CABLE/NATHAN SUMMERS
When he was first introduced in the 80s, the argument could have been made that Cable was the most powerful mutant in the Marvel Universe. While he's since been surpassed by some of the other mutants on this list, as the son of Scott Summers and a Jean Grey clone, the time travelling cyborg won the genetic lottery when it comes to powerful mutant abilities. He inherited his mother's telepathy and telekinesis; however, due to the techno virus that he contracted, he's unable to use them to their full extent. In spite of this, he still has incredible abilities which include mind control, flight, psionic shielding, psionic blasts, illusions, and matter control at a molecular level. He can also time travel and link his mind to the Infonet to gather information.
Additional abilities are granted to him by his various techno-organic implants. He has a bionic gauntlet armed with rockets which gives him super-strength, as well as a cybernetic eye that allows him to see in infra-red and fire an optic laser. At his full potential, Cable could lift a city into orbit; at his weakest, he could single-handedly take on half of the Avengers.
PROFESSOR CHARLES XAVIER
It makes sense that the man who created the X-Men should also be among the most powerful. Though he's a cripple confined to a chair, he's often regarded as the most powerful telepath who has ever liveda status that places him among the most important and influential people in the Marvel Universe. He's also a part of the Illuminati, a clandestine organization of peace-keeping geniuses which also includes Reed Richards and Tony Stark.
Professor X never had to do too much fighting himself, since that's what the X-Men are for, but should the need arise, he has the ability to probe the minds of others to do things like erase memories, induce feeling of excruciating pain, or even wipe out your entire personality, leaving you nothing more than a drooling vegetable.
EMMA FROST
Though Emma Frost started out as the villainous White Queen of the Hellfire club, she has since joined the X-Men and holds a position of authority with them and at Xavier's School for Gifted Youngsters. In addition to having telepathic powers that are almost on par with Professor X, Emma Frost has the ability to alter her body's molecular structure and transform her skin into diamondsort of like Colossus's mutant powers, but better since diamond is harder than metal. While in that form, her telepathic powers are diminished but her strength and durability go through the roof.
During her tenure as a villain she was especially known for the using her telepathy to control the minds and bodies of others. Her control over her psionic abilities is so precise that she's learned to rewire the neural pathways of other mutants to boost their powers. So ya, she's pretty damn powerful.
MAGNETO
Although better known as the nemesis to Professor Xavier and the X-Men, Magneto has actually been part of the team on several occasions, teaching the New Mutants and even leading the X-Men.
His central power is the ability to control magnetic fields (he's also a genius with an impressively long life span), which doesn't necessarily seem all that amazing at first glance. Why is the power to be a human magnet as impressive as some of the other reality-controlling mutants on this list?
The thing is, magnetic field control isn't just about making metal objects fly around (although that's pretty cool, and something we see the most often). Everything in the world has a magnetic field, and he can manipulate all of them without breaking a sweat. This ability allows him to fly, manipulate magnetic fields around electricity and power, create force fields, and even affect telepathy (which would suggest he could potentially use his power for mind control as well). Essentially, he is an absolute badass who is more than worthy of going toe-to-toe with Professor Xavier (and gives fans a little lesson on magnetic fields while he's at it).
HOPE SUMMERS
This Omega level mutant was born with vast power, but as of yet it hasn't been fully realized in her. Her birth itself sent out a psionic pulse that destroyed Cerebro, and she has been hailed as both the Mutant Messiah and the harbinger of humanity's death.
Various different powers have emerged from her at different times. She healed Rogue as a baby, and as a teen and adult she has shown telepathy and telekinesis powerful enough to stop a bullet. She has also revealed pyrokinesis, turned parts of her body into organic metal and fired psionic blasts. She, like Jean Grey, is connected to the Phoenix Force but she cannot control this connection in any way, and he powers have manifested when she is emotional or under threat. Her powers have been described as both mimicry (being able to repeat any power that she sees, much like Rogue can, but without time limits or the need for physical contact) and as the combination of every mutant power currently in existence.
ICEMAN/BOBBY DRAKE
Since he's regularly been portrayed as a brash teenager, Bobby Drake is often overlooked as one of the most powerful X-Men. But perhaps more so than any other member, Iceman has steadily evolved his powers over the years to the point that he's now classified as an Omega Level mutant.
Using his thermokinesis, Iceman can lower his external and internal body temperature, allowing him to project intense coldness from his body. Though when he was just learning to control his powers Bobby was only able to cover his body in snow and ice, with the help of Emma Frost he was able to further develop this ability so that he can now transform every molecule in his body to any state of water, making him virtually invincible and allowing him to travel at incredible speeds through large bodies of water. He also has thermal vision and can absorb water molecules or vapour into his body to greatly increase his size and strength. The most recent advancement of his powers saw him gain the ability to generate autonomous ice clones of himself with various appearances and strengths. It is unknown exactly how many of these clones he can create.
If Iceman continues to probe the depths of his powers like this and learn to use them in new and imaginative ways, he could one day become the most powerful mutant in existence.
MAGIK/ILLYANA RASPUTINA
Even though she might not be as well-known as her brother Colossus, Illyana Rasputina is definitely the more powerful of the two siblings. Known as the X-Men's Magik, she has two very distinct sets of powersone mutant related, and other stemming from magic. Her mutant ability is teleportation, which she controls through "stepping discs" that allow herself and others to teleport across interstellar distances, travel through time, or even transverse dimensions. While in the Limbo dimension she learned the sorcerer's arts to become Sorcerer Supreme, including astral projection, metamorphosis, necromancy, force fields, possession and the creation of magical constructs. llyana also learned both black and white magic and acquired a partially demon soul that granted her psionic shielding. But the crown jewels of Magik's abilities would have to be the Soulsword and Eldritch Armor, which in effect make her invulnerable to any magic attacks and enable her to destroy anything that uses magic.
As if both mutant and magic powers weren't enough, after the events of Avengers vs. X-Men, Magik was imbued with the Phoenix Force.
JEAN GREY/PHOENIX
Despite her humble beginnings as a pretty basic telepathic/telekinetic, Jean Grey's affiliation with the Phoenix Force has resulted in her having near-infinite powers.
Jean has probably died more times than any other character in the Marvel Universe, and each time she comes back stronger than before, much like a phoenix rising from the ashes. Her telepathy and telekinesis enable her to control and hypnotize others, fly, create force fields, project concussive blasts, manipulate matter at the subatomic level, and open wormholes that let her travel through the universe faster than light. Her power is so great that she strikes fear into the hearts of other Omega mutants like Magneto, and has tried to be controlled on numerous occasions by powerful entities like the Hellfire Club (unsuccessfully, mind you).
However, sometimes Jean's Phoenix powers can go to her head and make her a bit crazy. Like that time she became Dark Phoenix and devoured an entire star along with the five billion inhabitants of a nearby planet. Still, that's exactly the kind of display of raw power that earns you the top spot on the most powerful X-Men of all time list.
STORM/ORORO MUNROE
Considering that naturally occurring weather patterns can leave entire cities in ruins in a matter of minutes, you can imagine that a mutant with the ability to control those elements would be pretty powerful. That mutant is Ororo Munroebetter known as Storm. She can control winds that allow her to fly, channel lightning bolts, manipulate environmental electrical energy and even augment her vision to enable her to see electrical energy patterns. Her powers are also adaptive, which means she's able to survive in environments found on other planets or other realms and still control the elements there. Furthermore, Storm has a heritage of magic and witchcraft that makes her one of the most powerful Magic users in the Marvel Universe and protects her mind from most psychic attacks. With powers like that it's no wonder she's revered as a Goddess in certain parts of the world.
X-MAN/NATE GREY
Nate Grey is an Omega level mutant genetically engineered during the Age of Apocalypse timeline from the DNA of Scott Summers and Jean Grey. He was designed as the ultimate mutant with telepathic and telekinetic abilities, and when he escaped from his test tube environment, he learned to use some of his powers and managed to kill Apocalypse, sending himself from their reality to Earth 616.
Nate is constantly trying to control and expand his powers, and at times has been almost unstoppable (as the Mutant Shaman), but his abilities have made him a target since he was first created. Multiple factions and other mutants have tried to control and use him, even using him as a power source to open portals to other realities (he's just that powerful). However, his time in the Omega machine burned out most of his powers, and he is now in the process of attempting to regain his abilities, which drops him to the bottom of this list.
Psylocke
Possessing awesome ninja skills and the ability to create incredible psionic and telekinetic weapons, Psylocke has always been one of the coolest characters to ever find a place on the X-Men's roster. In addition to being a master martial artist and one of the world's most powerful telepaths, Psylocke can teleport, create force fields, disrupt opponents' nervous systems with her psionic blades, and fire energy blasts like she's freakin' Vegeta.
After having her full mutant potential unlocked by a Jean Grey from an alternate universe, Psylocke reached Omega Level status and could pretty much go toe-to-toe with some of the biggest baddies the X-Men have ever faced. Personally, we can't wait to see her portrayed by Olivia Munn in X-Men: Apocalypse.
LEGION/DAVID HALLER
David Haller is the estranged son of Charles Xavier, and, as such, perhaps it shouldn't come as a surprise that he's also a mutant with Omega Level powers. As Legion, David has an incredible assortment of abilities that include pyrokinetic telepathy, super strength, super speed, healing, probability manipulation, reality warping, and even time travel. Basically there's almost nothing he's incapable of, the only problem is that he has a lot of trouble controlling his powers.
When still a child, David's home was attacked by assassins and he watched as his step-father was killed right in front of him. The terror he experienced in that moment had the effect of catalyzing his latent psionic powers, which he then used to incinerate the brains of the assassins. However, in the process he made telepathic contact with each of his victims, thus experiencing all their thoughts and emotions in the moment of their death. The horror of the ordeal put David in a catatonic state for most of his formative years. When he finally emerged from the state, it was revealed that the trauma had shattered his mind, leaving his core persona floating in a sea of other personas within him. Each of these personas controls a different one of Legion's fantastic mutant powers. So although he has the potential to do pretty much anything, it's very hard for him to use his powers in combination.
