• Flight of herself at Remarkable air speed, or up to ten other people at Excellent speed
• Create a shield of Incredible Intensity against physical attacks
• Project Force bolts of sheer Telekinetic energy that hit with Incredible Agility and do Incredible damage

When Jean was eleven she went to Professor Charles Xavier, who was secretly a mutant with telepathic abilities. Xavier explained to Jean, but not to her parents, that she was a mutant, and he treated her for several years. During this time he erected psychic shields in Jean’s mind so that she would not be able to use her telepathic abilities until she had achieved the maturity necessary for dealing with them. Simultaneously, he taught her how to levitate and manipulate objects through psionic force. When Xavier judged that Jean had reached mastery of her telekinetic power, he enrolled her in his School for Gifted Youngsters. She took the code name of Marvel Girl. Shortly after she joined the X-men team, Grey and Scott Summers, the X-Man known as Cyclops, fell in love with each other.

When Xavier realized that he had to remain in isolation for an extended period of time in order to make preparations to thwart an attempted invasion of Earth by the alien X’nox, he released the psychic barriers preventing Grey from using her telepathic abilities.

Sometime later, after Xavier had recruited several new members for the X-Men, Grey and some of the other X-Men decided to leave the group in order to lead their own lives. Scott Summers remained in the X Men, but he and Grey continued their romantic relationship. Shortly after she left the team, Grey and the then-current members of the X-Men were kidnapped by Steven Lang’s Sentinels and taken aboard Lang’s space station. After defeating Lang, the X-Men had to escape back to Earth aboard a space shuttle during a solar radiation storm. The design of the craft required the pilot to sit in an area without protective shielding. Grey volunteered to be pilot, figuring her powers would hold back the radiation. But the radiation proved to be too great, and Marvel Girl began to succumb.

It was long believed that Grey had indeed died aboard the space shuttle but became linked with a primal energy force known as the “Phoenix Force” which recreated and reentered her body. The vastly more powerful being took the code name Phoenix and joined the X-Men. Phoenix fell victim to psionic manipulation by Mastermind, who was attempting to prove his worthiness to become a member of the Inner Circle of the Hellfire Club by mesmerizing Phoenix into becoming its new Black Queen. He psychically induced dark, repressed desires from within Grey’s subconscious to come to the surface of Phoenix’s mind, submerging Grey’s true normal personality. Grey/Phoenix finally freed herself of Mastermind’s control, but was unable to prevent the dark side of Grey’s personality with the full power of the Phoenix Force behind it, from overwhelming her, not having had the training necessary to repress it. Grey’s true personality was submerged more fully than before, and Phoenix became the malevolent Dark Phoenix. After Dark Phoenix wreaked incredible devastation, Grey’s true personality reasserted control of Phoenix once more, and, before Cyclops’ horrified eyes, Phoenix committed suicide rather than revert to Dark Phoenix.

But recently it was revealed that Grey had not died, nor had she ever become Phoenix. The Phoenix Force had responded to Grey’s anguish and telepathic calls for help as she was dying aboard the space shuttle, and appeared before her, shaping its form and consciousness after Grey’s own. The force told Grey that she was dying, but that by taking the force’s hands, Grey would gain her “heart’s desire.” What Grey most wanted was to save the lives of the X-Men and herself. She held onto the Phoenix Force’s arm and fell into a coma-like state. Simultaneously, the being fully took on both the form and the memories and personality of Jean Grey, casting Grey into a coma-like state and placing her within a podlike construction, which rested for years at the bottom of Jamaica Bay while Grey’s injuries healed completely. Thus the Phoenix Force fulfilled its pledge to Grey.

The Phoenix Force creature compelled itself to believe it was indeed Grey, whose personality it had assumed. It has been theorized that it was the entity’s own power rebelling against the duplicate of Grey’s personality it had given itself that caused it to become Dark Phoenix. When Phoenix committed suicide, it was acting exactly as Grey herself would have done.

Many months after Phoenix’s death, the Avengers found Grey’s pod beneath Jamaica Bay and brought it to the Fantastic Four for study. Releasing herself from the pod, she recalled what had happened and learned the story of Phoenix. Grey somehow lost her telepathic powers, but the strength of her telekinetic powers had greatly increased.

Grey was greatly disturbed to learn of the current wave of anti-mutant sentiment in the country, Xavier’s recent disappearance, and the fact that the current X-Men were now working alongside Magneto, the original X-Men’s greatest foe. Grey and the other original X-Men founded X-Factor, a new organization to help other superhuman mutants.