5. Nate Grey (Marvel Comics)
Without a doubt, one of the coolest characters in all of comics let alone the X-Men comics is Nathaniel "Nate" Grey (also known as "X-Man"). Originally created artificially by Mister Sinister, using the DNA of his universe's Scott Summers and Jean Grey, Nate is essentially an alternate reality version of another X-Men character Cable (and, although their powersets are meant to be pretty much the same, Nate has certainly portrayed himself as consistently more powerful). Despite not originating there, using his cross-dimensional powers, Nate has ended up in the main (616) Marvel universe and has represented both the sides of good and evil. Having been created to be the ultimate mutant, he is what is known as an Omega level mutant and, in addition to his cross-dimensional powers, Nate possesses extremely high level telepathy and telekinesis that enables him to lift very large and heavy objects and essentially fly (at supersonic speeds, nonetheless). Indeed, he was powerful enough to single handedly defeat Tundra of the Great Beasts and was even able to psionically isolate the planet's gravitational pull on the two other Great Beasts, Lolomaq and Somon. In fact, he once inadvertently telekinetically crushed an entire town while he slept. To put this in to perspective, he was once measured as having a psionic energy output matching that of the Dark Phoenix. He possesses the extra-sensory ability of psychometry (the ability to learn more about an object's history by "reading" it), precognition and the ability to exist as living energy meaning that he essentially can't die, because his essence will live on even once his body is destroyed.