Magneto is a powerful mutant, one of a fictional subspecies of humanity born with superhuman abilities, who has the ability to generate and control magnetic fields. His extreme methods and cynical philosophy derive from his "Never again" determination to protect mutants from suffering the same fate as the Jews at the hands of a world that fears and persecutes them. He was once a friend of Professor X, the leader of the X-Men, but their differing philosophies caused a rift in their friendship. Magneto's role in comics has progressed from supervillain to antihero.

Mystique has been both a supervillain and an antiheroine who is often depicted as a high ranking member of the Brotherhood of Mutants, having both served and led the organization in its fight against humanity by assassinating several important people involved in mutant affairs. She has the mutants power of shape shifting and accelerated healing

Xavier is a member of a subspecies of humans known as mutants, who are born with superhuman abilities. He is an exceptionally powerful telepath, who can read and control the minds of others. To both shelter and train mutants from around the world, he runs a private school in the X-Mansion in Salem Center, located in Westchester County, New York. Xavier also strives to serve the greater good by promoting peaceful coexistence and equality between humans and mutants in a world where zealous anti-mutant bigotry is widespread.

As a member of the X-Men, Wolverine has built strong relationships with many of his teammates, being close friends with Nightcrawler and Storm, with whom he also has an on-again, off-again relationship. He has also harbored feelings for Jean Grey, which has led to clashes with her husband and X-Men leader Cyclops. He possesses a range of superpowers including highly advanced self-healing abilities, a significantly prolonged lifespan, animal-keen senses, and retractable claws.

Scott Summers is the older brother of Havok. His first and most enduring love interest is his wife, Jean Grey. Cyclops is a member of a subspecies of humans known as mutants, born with superhuman abilities. Cyclops emits powerful beams of energy from his eyes and can only control the beams with the aid of special eyewear, which he must always wear.

Jean Grey is a member of a subspecies of humans known as mutants—individuals born with superhuman abilities—with Jean possessing psionic powers. Initially capable of using only telekinesis, she later develops the power of telepathy. During her early stint with the X-Men, she used the codename Marvel Girl. Jean is a caring, nurturing figure, but she also has to deal with being an Omega-level mutant and the physical manifestation of the cosmic entity known as the Phoenix Force. Jean first experienced a transformation into Phoenix in the X-Men storyline "The Dark Phoenix Saga". Due to Mastermind's manipulations, Jean's psyche was twisted and she became Dark Phoenix during "The Dark Phoenix Saga", before sacrificing herself to prevent any further chaos. After her presumed death, Jean would return and resume her relationship with Cyclops, whom she married.

Jubilee is a member of the human subspecies known as mutants, born with superhuman abilities. She can generate pyrotechnic energy blasts from her hands. Introduced as an orphaned "mall rat" from Beverly Hills, Jubilee joined the X-Men in the early 1990s, becoming the team's youngest member and often playing a sidekick role to her father-figure, Wolverine.

Nightcrawler, the superhero identity of Kurt Wagner, is a member of a fictional subspecies of humanity known as mutants, who possess an X-gene that can cause possible physical mutations and in many cases grants some form of superhuman ability. Nightcrawler possesses superhuman agility, the ability to teleport, and adhesive hands and feet. His physical mutations include indigo-colored velvety fur which allows him to become nearly invisible in shadows, two-toed feet and three-fingered hands, yellow eyes, pointed ears, and a prehensile tail.

Gambit can mentally create, control, and manipulate pure kinetic energy. He is also incredibly knowledgeable and skilled in card throwing, hand-to-hand combat, and the use of a bō. Gambit is known to charge playing cards and other objects with kinetic energy, using them as explosive projectiles. Gambit is from New Orleans. He speaks Louisiana French and Cajun English.

Rogue is depicted as a mutant, a subspecies of humans born with an "X-gene" that grants superhuman abilities. She is capable of absorbing the life force, attributes, memories, and superpowers of anyone through physical touch. The character is initially portrayed as a reluctant supervillain, but she soon joins the X-Men as a superhero and has since endured as one of its most prominent members.