Lilith, one of the most powerful and dangerous beings in the universe, or multiverse, depending of facts.
Here's some information to get into context:
Lilith is really Kairi (from Kingdom Hearts), but in a reality where the Keyblade War went completely to the worst. After all her friends (Sora and Riku included, except Mickey) die destroying the Organization XIII, she ends having an epiphany. As Xehanort, she believes that while Light keeps pushing away Darkness, this will always cause chaos. After seeing she has no place in the World of Light, she rids herself of her pure light, and turns herself into what many people call 'the embodiment of darkness', the queen of darkness, the Dark Phoenix. Dropping out her old name Kairi, she took the devilish name of Lilith.
Her Dark Phoenix surname and second form (the winged form at her side) is because, in this reality, she is the hybrid mixed-race daughter of a female human, and ancient Eidolon Phoenix (The usual summon beast of the Final Fantasy Franchise https://www.creativeuncut.com/gallery-34/ffbe-phoenix.html )
