Maleficent (KH III: Reconnect)

The Mistress of All Evil, Maleficent has returned from her defeat in KH 3D to finally begin her plot to conquer all worlds by capturing the 7 Princesses of Hearts once more to open Kingdom Hearts itself, since her plan stated in 3D, using the data of the worlds obtained from Jiminy Cricket's Journal, turned out to be pointless and useless to her needs, according to Dr. Facilier, that is. But now, she's discovered that there are MORE princesses of Heart in the galaxy than what was originally thought to be, as a result of Xehanort's machinations to obtain the main original 7 to recreate the X-blade. Her hatred and spite have given her greater control over the Heartless and Dream Eater Nightmares, as well as the newly arrived Heart Eater clan and returning Goblin Goons. She's even gathered new allies to replace her fallen comrades.

Eventually, Maleficent remembers something that she learned from her demonology scrolls that she read under her apprenticeship to the Horned King. Searching through the old scrolls, Maleficent discovers the prescence of a "true" Chernabog that is said to be the most powerful of all dark beings in the universe. Seeking to finally ally with the mysterious being that's responsible for "all the powers of Hell", she decides to search through her scrolls to look for an infernal spell that will allow her to summon Chernabog under her command, while also collecting the souls of her destroyed allies as possible sacrifices to the demon king's power.

This desire to become one in partnership with Chernabog slowly maddens Maleficent to the point that she is willing to recreate the Keyblade of People's Hearts from all 7 of the original Princesses of Heart, and stab herself with that blade so that she can finally become darkness itself.

Quotes from the Game
Conversation with Master Xehanort during Midpoint


 * Maleficent appears in the World that never was*
 * Maleficent: What a sight... the castle is still intact even after all that has occurred so far.
 * MX: Maleficent? Why are you here? You were the last individual I expected to come here so late into my plan.
 * Maleficent: Oh, you old, senile fool. You thought I would let you get away with manipulating my actions? And what's worse, making me plot schemes to hunt a worthless journal compared to what you were doing in the meantime?! You should have known better.
 * MX: Heh, you caught me, my dear. I suppose you would try to slain me right now on the spot. But I'm afraid here you have no power. Not over the darkness or over the heartless.
 * Maleficent: That is where you are wrong, Xehanort. I do not need either of those. You see, I already was able to create my own spells without having the use of the darkness you so longingly preach.
 * MX: *Looks inquisitively at the faerie* What do you mean?
 * Maleficent: I still hold sway over the power of sleep. You might be able to interfere into dreams, just like what you did to plunge the Keyblade Wielder into an averted sleep, but I can stir them and their hearts to my content! Just like what I can do with your so-called ability to control the Dream Eaters! *She uses her staff to cast an evil spell, causing the old man to glow green and groan in pain. When the glow disappears, Xehanort realizes that he can no longer control the Dream Eaters!*
 * MX: NO!  My army! You shall pay for your interference, witch! *disappears into corridor*
 * Maleficent: Heh... run all you like, old man... but you can't hide from me... ME, THE MISTRESS OF ALL EVIL!