Cassandra Nova is a
mummudrai, a parasitic entity who began life at the same time as
Charles Xavier. Conceived without a body, Nova copied Xavier's DNA to make her own body, effectively making her his twin sister. She grew with her brother until she had fully formed hands and eyes, when she decided to try to kill Xavier by attempting to strangle him with his own umbilical cord. Xavier defended himself by hitting her with a psychic blast, which caused their mother to have a miscarriage, resulting in her physical body being
stillborn. Nova survived as a mass of cells that clung to a sewer wall for decades, rebuilding her physical form and swearing revenge on Xavier. Nova manipulates Donald Trask (a relative of
Bolivar Trask) to utilize the
Wild Sentinels to devastate
Genosha, killing 16 million
mutants. Nova duplicates Trask's DNA to gain control of the Wild Sentinels, then kills him. Nova is captured by
Cyclops and
Wolverine and taken to the
X-Mansion, where she escapes and defeats most of the X-Men easily. Nova uses Cerebra, an enhanced version of
Cerebro, to switch bodies with Xavier. Xavier is trapped in Nova's body and unable to warn the X-Men before Nova shoots him. .|left Nova contacts the
Shi'ar and manipulates them into battling the X-Men until they show the truth to the
Imperial Guard. Angered at Nova's treachery and realizing the danger she poses, the Imperial Guard battle Nova, who defeats them and heads to the X-Mansion. She plans on using Cerebra to eliminate all mutants, but
Jean Grey stops Nova and forces her out of Xavier's body. Nova's essence is tricked into entering the body of Stuff, a shapeshifting member of the Imperial Guard. There, she is locked in a self-repeating program. Influenced by Nova and her own guilt over the Genoshan massacre, Frost created illusions of her younger self, Nova, Shaw, and
Negasonic Teenage Warhead, a student of Frost who was killed in Genosha. Frost and the Hellfire Club attack the X-Men, only to be defeated by Cyclops and the Xavier Institute students. Nova escapes from the X-Men's clutches by using her psychic powers to possess the bodies of others. She also creates microscopic
Sentinel technology that transforms humans into Sentinel-like forms, causing them to mindlessly attack mutants. With the help from the
Avengers and the
Atlanteans, the X-Men mass-produce
Magneto's helmets to free Nova's brainwashed victims. During the
Krakoan Age, Nova moves to the mutant nation of
Krakoa, having been given a second chance per the island's laws. She resides in a hidden section of Krakoa, away from the
Quiet Council's influence. Nova goes on to work with Krakoa's
Marauders team. Sometime after the
fall of Krakoa at the hands of
Orchis, Cassandra Nova joins the group
3K, who intend to give mutant powers to humans and have mutants outnumber humans by the year 3,000. ==Powers and abilities==