The alias of the Phoenix has been used by several characters in comics published by Marvel Comics. The first one, Baron Zemo, only used that alias once, but the later bearers of the identity are far more notable, and all are associated with the Phoenix Force. The Phoenix Force is famous for its central role in two of the most important storylines in comics: the Phoenix Saga and the Dark Phoenix Saga (the two storylines may also be regarded as one extended storyline).

The Phoenix Force is a powerful extra-terrestrial entity which possesses mortals and amplifies their psychic abilities. Its known hosts have included Jean Grey and Rachel Summers, both members of the X-Men. The entity did not physically possess Jean Grey; instead, it created a second body identical to hers and through that body acted for her while she lay in a coma. However, the Phoenix was unable to adapt to its newfound humanity and was driven mad; as the Dark Phoenix, it destroyed a planet populated by sentient creatures and subsequently committed suicide. Jean Grey was later revealed to be alive, and later reassumed the name of the Phoenix after marrying Cyclops.

Another person to assume the Phoenix identity is Rachel Summers, Jean's daughter from an alternate future. She bears an uncanny resemblance to her mother.

Most recently, Jean began manifesting the attributes of the Phoenix Force. Despite this, she generally retained her self-control until her death at the hands of someone posing as Magneto.