E Is for Extinction

As we cut through multiple action shots—more of Wade fighting TVA agents like we saw in the first trailer, a little more of his scrap with Logan—we get our first proper look at Emma Corrin’s villain: and while their name isn’t mentioned anywhere in this trailer, there’s no way this isn’t Cassandra Nova.
Introduced in the legendary opening arc of Grant Morrison and Frank Quitely’s New X-Men in 2001, Cassandra is what is known to the Shi’ar Empire as a “Mummudrai”—a sinister manifestation of the self that all beings face in the womb. Cassandra was the Mummudrai to none other than Charles Xavier, taking a form and a semblance of his mutant abilities in utero while trying to murder him. Xavier fought back and seemingly killed his “sister” before he was even born, but Cassandra’s hate and vast psionic power lead to her surviving for decades after stillbirth, taking a shape not too dissimilar to Charles’ and plotting her vengeance in secret. It started with convincing the heir of Bolivar Trask’s legacy in the Sentinel Program to help her activate a Master Mold factory, deploying Sentinels to almost entirely wipe out the 16 million mutants that had made the isle of Genosha a new mutant state.