Genetically engineered to be the most powerful mutant who ever existed, Nate Grey (aka X-Man) is the "son" of Scott Summers (Cyclops) and Jean Grey from the Age of Apocalypse reality (Earth-295). His abilities are so vast that he can create or destroy entire worlds with ease, and he is way more powerful than his more famous alternate version, Cable.

The Age of Apocalypse was accidentally created by Legion, son of X-Men leader Professor Charles Xavier, who used his own vast powers to tamper with the time stream and inadvertently killed his own father. The result is a war-torn world where the mutants, led by Apocalypse, are the dominant race, and most of the humans have been enslaved or killed. In this reality, Mister Sinister creates a baby from the genetic material of Scott Summers and Jean Grey, altering him to be the most powerful psychic in the world. Sinister wants to use him for his own bid for power against Apocalypse, but Nate escapes and is raised among peaceful mutants. When he grows up, he joins a rebellion against Apocalypse, and during a battle against the tyrant's son Holocaust they are both transported into Marvel's core reality, Earth-616.

Related: X-Men's Age of Apocalypse Is Still Marvel's Best What If? Story

In this new world, Nate's immense power immediately attracts the attention of friends and foes. He is the most powerful telepath (even if not the most skilled) in the world. On one occasion, he is able to mind control powerful individuals such as Omega Red, Legion, and Magneto at the same time. He is also shown communicating across the Multiverse and sending a message to every person on Earth. Even more powerful is Nate's telekinesis, which has almost no limit. He can move the tectonic plates of a planet, and disassemble and alter molecular and atomic structures. Nate was once described by Moira McTaggert as a psionic who rivals a Phoenix Force-imbued Jean Grey, however, these are just his most basic powers. X-Man is also a reality-warping mutant who once created his own place of existence (called the Age of X-Man), which he molded into a mutant paradise.

Nate Grey X-Man faces the X-Men

The X-Man ongoing series, which lasted for 76 issues between 1995 and 2001, did a great job in constantly hyping up Nate's powers and the fact that he is the most powerful mutant who ever existed. He is obviously an Omega Level mutant (but that's a reductive description), and he has been referred to as the most powerful and most dangerous being on the planet, the ultimate mutant, and the most powerful psionic in all of reality. However, it was Norman Osborn who, during his Dark Reign, recognized Nate's potential more than everyone else, calling him a living god. Unfortunately, X-Man's encounter with Norman Osborn ended with Nate being defeated by the Dark X-Men and the Dark Avengers, and then trapped in the Omega Machine, a fearsome contraption used to siphon off his powers. He was rescued by the New Mutants and went to live on Utopia island, but Nate's abilities were reduced to those of a "normal" psionic and he was nowhere near his previous level.

Later, Nate recovered his full power using a Celestial artifact called a Life Seed and actually became even stronger than before, if that was even possible. He has since been classified as "above Omega Level." However, his lifespan was meant to be short from the beginning, as Mister Sinister put a "time bomb" into his genes when he created him. With his death approaching, Nate wanted to make the world a better place - by force - which put the X-Men against him. As a result, Nate Grey acted in true godlike fashion, creating his own reality, and is currently trying to make that world perfect, leaving Earth-616 alone.

This is perhaps for the best, as no other mutant comes even close to Nathaniel Grey, the most powerful mutant who ever existed.

Next: Iron Man Got a Ghost Rider Upgrade in X-Men's Darkest Timeline