Fifth and final of the team's founding members, although she had met Xavier before the others. Left the team in X-Men vol.1 #94. Rejoins at the end of the Muir Island Saga, X-Factor vol. 1 #70. Ex-wife of Scott Summers. She was killed by Kuan-Yin Xorn in New X-Men, vol. 1 #150 (2004) and was later resurrected by the Phoenix Force in X-Men: Phoenix – Endsong (2005) as White Phoenix of the Crown.

Powers: Possesses telekinesis and telepathy. As the template of the Phoenix Force, she is able to generate unlimited amounts of energy, travel through time-space, and manipulate matter on a subatomic level.