X-Men: 10 Worst Things The Mutants Have Done

The Dark Phoenix Saga is one of the X-Men's most popular storylines and deservingly so. When Jean Grey is manipulated by the Hellfire Club, the barriers of her powers are destroyed, which corrupts her as she transforms into the Dark Phoenix.

When the entity is drained by recent events, the cosmic force devours the energy of a D'Bari star which causes the deaths of every inhabitant on a nearby planet. In just a few panels, Jean Grey, through the Dark Phoenix, has basically committed genocide.

This forces the Shi'ar Empire to take action and conclude that Grey has become a threat that rivals the likes of Galactus. They sentence her to death due to the risk she poses, but the X-Men challenge the alien empire to a fight on the moon; one that will free Jean should they win.

Though the X-Men lose the climactic duel, Jean realizes the threat she has become and kills herself to prevent the Dark Phoenix from harming anyone else. Ultimately, as the Watcher said, Jean Grey chose to die as a mortal than live as a god.