New X-Men
Cassandra Nova seizes control of Professor Xavier's body while the Xavier Institute goes public, transforming the X-Men from a covert superhero team into the face of an emerging mutant culture
Cassandra Nova hijacks Xavier's body. The school goes public. Morrison establishes mutant culture as a real thing — fashion, music, drugs, politics. The X-Men stop being a superhero team and start being a species
The scope expands. Cassandra Nova hijacks Xavier's body and travels to the Shi'ar Empire to destroy everything he built. Meanwhile, the X-Men deal with a world that now knows Xavier is a mutant. Jean's Phoenix powers resurface. Xorn, the mutant with a star for a brain, is introduced in a standalone issue (#127) that ranks among the best single X-Men issues ever written