Selene is the oldest known human mutant. Functionally immortal, her millennia-long life is attributed to her ability to drain the life essence from other beings to extend her own existence indefinitely. Her name derives from the ancient lunar goddess Selene, daughter of the Titans Hyperion and Theia.
It was once believed Apocalypse was the first mutant in the world. He was born in ancient Egypt around 3000 BC. But in X-Force it was revealed that Selene the Black Queen is a mutant who predates Apocalypse. She was born in 15000 BC which is around 12,000 years before Apocalypse.
Able to regenerate from any and all injuries, including death, Craig Hollis is unable to die and therefore dubs himself Mister Immortal, vowing to fight crime.
The Legion, who Magik called "The God Mutant," appeared and altered reality to wipe the Elder Gods from existence and reset the world to a time before they had manifested.
Long-time fans of the X-Men franchise will not be surprised to learn that the title goes to Charles Xavier's own son, David Haller, aka Legion, who has the power of countless Omega-level mutants trapped in his usually unstable mind.
The first recorded (with a clear date) human mutant on Earth was Selene, born in Central Europe 17,000 years ago, "after the Oceans swallowed Atlantis" and "before the rise of the sons of Aryas", during the Hyborian Age, and even clashed with Kulan Gath over 10,000 years ago.
With enough preparation, Apocalypse would have a surprisingly decent chance at beating a Gauntlet-free Thanos. Apocalypse has trained and fought wars for centuries, mastered many forms of combat and magic, and all of that could very well be enough to topple Thanos, especially if he didn't have the Infinite Gauntlet.
Kitty is probably the youngest mutant to ever join the X-Men. She wasn't more than 13 when she became a member of the team. Looking back, Kitty didn't even go through training in the New Mutants or Generation X. Her trial of fire began immediately.
Namor is commonly referred to as "Marvel's first mutant." He may not be as old as ancients like Selene and Apocalypse, but he does have the distinction of being the first mutant character to actually appear in a comic book (1939's Marvel Comics #1, to be specific).
The results shown presented the following as Alpha-Level Mutants: Franklin Richards, Phoenix, Legion, Professor X, Storm, Namor, Sebastian Shaw, Havok, and Sinister (though he was not classified a mutant at the time).
An Omega-level mutant is one with the most powerful genetic potential of their mutant abilities. The term was first seen in the 1986 issue Uncanny X-Men #208 as "Class Omega", but was completely unexplained beyond the obvious implication of it referring to an exceptional level of power.
Adam Monroe. Adam originally possessed the ability Enhanced Regeneration. However, because he regenerated so much in his wars his body eventually stopped aging and he became Immortal.
Selene is the oldest known human mutant. Functionally immortal, her millennia-long life is attributed to her ability to drain the life essence from other beings to extend her own existence indefinitely. Her name derives from the ancient lunar goddess Selene, daughter of the Titans Hyperion and Theia.
Deadpool's not a mutant. His powers come from experiments carried out by the Canadian military, not from a mutant X-Gene. What makes it a little confusing is that the experiments were attempts to duplicate Wolverine's powers, so while he's not a mutant himself, his healing factor is derived from mutant biology.
Quire explains to the rest of X-Force that in this timeline, Beast cultivated fear between humans and mutants, channeling that power into his own religion. Quire says that, over time, the Beast has morphed into “the God of All Mutants.”
In some cases, a mutant might fall under two different classifications if they have multiple powersets. Wolverine's enhanced senses are a Beta Level powerset, while his healing factor makes him an Alpha Level Mutant. In these situations, the mutant is classified based on whichever powerset is the strongest.
Cyclops' brother, Havok, is one of the few Marvel superheroes who can defeat the Hulk in a fair fight. Alex Summers aka Havok may not be as popular as his more famous brother, but he is easily one of the most powerful mutants in the Marvel Universe.
Class 5 or Omega mutants is a category reserved for the elite of the mutant community, blessed with unlimited genetic potential. For a long time there was only Jean Grey, the first, however over the last couple of decades many more have sprung up or been reclassified.
Half of Cap's Kooky Quartet, Quicksilver and the Scarlet Witch, were not only mutants, but were former members of the Brotherhood of Evil Mutants. Other mutant aventures include Beast, Rogue, Havok, and Wolverine.
