Phoenix (Marvel Comics)

Phoenix is a force in the Marvel Comics universe with extremely powerful psionic abilities. It occupied different hosts at different times, including Jean Grey and Rachel Summers. The power gained by the host was often offset by the exponential rise in the host's flakiness[?], which would frequently render the host useless when needed most, thus keeping the team from getting too powerful.

The character Jean Grey was introduced as a member of the X-Men in the early 1960s, and Rachel Summers was introduced as a member of the British-based superhero group Excalibur.