Jean Elaine Grey-Summers is a character appearing in American comic books published by Marvel Comics. Created by writer Stan Lee and artist/co-plotter Jack Kirby, the character first appeared in The X-Men #1 (September 1963). 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 developed 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 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. Following her return, Jean fostered relationships with Rachel Summers, her daughter from an alternate future, and Cable, the son of Cyclops and Jean's clone Madelyne Pryor.

After Jean died a second time, Beast brought a younger time-displaced version of Jean into the present, alongside the rest of her original teammates. Eventually, Jean would be resurrected by the Phoenix Force once more, choosing to part ways with it and live her own life separately from it. Following her return, Jean briefly assumed leadership of the X-Men's Red Team, until the "Krakoan Age". Resuming her relationship with Cyclops following his resurrection, Jean would reconnect with the Phoenix Force, and choose to leave the X-Men to travel in space.

Jean's exact relationship to the Phoenix Force has often been changed throughout the character's history, as has her involvement in the events of "The Dark Phoenix Saga". Usually depicted as the Phoenix Force's favorite and most compatible host, storylines in 2024 revealed that Jean is actually the human manifestation of the Phoenix Force and its mother. Her connection to the Phoenix Force has often resulted in clashes with the Shi'ar Empire, responsible for the massacre of most of her family members.

Often listed as one of the most notable and powerful female characters in Marvel Comics, the character has been featured in various Marvel-licensed products, including video games, animated television series, and merchandise. Famke Janssen portrayed the character as an adult in the 20th Century Fox X-Men films, while Sophie Turner portrayed her as a teenager and young adult.

Jean Grey debuted under the codename Marvel Girl in The X-Men #1 (September 1963), created by writer Stan Lee and artist/co-writer Jack Kirby. The original team's sole female member, Marvel Girl was a regular part of the team through the series' publication. Initially possessing the ability of telekinesis, the character was later granted the power of telepathy, which would be retconned years later as a suppressed mutant ability.

Under the authorship of Chris Claremont and the artwork of first Dave Cockrum and then John Byrne in the late 1970s, Jean Grey underwent a significant transformation from the X-Men's weakest member, to its most powerful.

The first comic Claremont saw at Marvel after coming there in 1969 was the first X-Men issue penciled by Neal Adams (issue 56), after which he became enamored of Jean Grey. But when he started to write X-Men in issue 94, the first issue after the creation of the new team in Giant-Size X-Men 1, Len Wein had already established that she was leaving the team. The artwork was already done, and it was too late to change. But he promised himself he would bring her back as soon as possible, which he did in issue 97 when he became the sole writer of the title. Claremont also decided to upgrade her powers significantly.