cassandra nova

Cassandra Nova Xavier is a supervillain appearing in American comic books published by Marvel Comics, most commonly in association with the X-Men. Created by writer Grant Morrison and artist Frank Quitely, the character first appeared in New X-Men #114 (July 2001). She is a mummudrai, a parasitic life form born bodiless on the astral plane.
Cassandra is the twin sister of X-Men founder, the telepath Professor X (Charles Xavier). While in the womb together, Charles recognized her evil presence and killed her, resulting in her stillbirth.
The character made her live-action debut in the Marvel cinematic universe (MCU) film Deadpool & Wolverine (2024), portrayed by Emma Corrin.