10 Mutants Who QUIT The X-Men
5. Jean Grey
Jean Grey is one of the founding members of the X-Men and has one of the group's most storied histories. Although her powers were initially weak, Jean joined with the Phoenix Force, making her one of the most powerful beings in the Marvel Universe.
And, even without the Phoenix Force, Jean is classified as an Omega-level mutant. Omega is the classification reserved for mutants with the ability to wreak havoc on a grand scale like Jean's fellow Omegas Storm and Magneto.
The first time Jean left the X-Men was after the group's defeat by the Living Island Krakoa and the formation of the New X-Men. She was upset with Cyclops' decision to stay but remained close to many members such as Storm. Jean returned to service when anti-mutant terrorist, Steven Lang, took over a space station.
Because if you're going to kill a bunch of mutants... that's a pretty good step one.
During the mission, Jean saved the crew of a space shuttle by shielding it with her psionic abilities. However, the shuttle was hit by a solar flare, and her shields gave out. Jean received a lethal dose of radiation and called out telepathically for help. The Phoenix Force answered her call, and this was the second time Jean would leave the X-Men.
The Phoenix Force placed Jean in a restorative cocoon and hid her away while Jean's body healed. Following this, the Phoenix Force went on several missions with the X-Men posing as Jean Gray.
In the long history of her character, Jean has died and resurrected several times. She remains one of the most potent and exciting X-Men to date.