|“||You would not understand, nor could you understand. That is why I must do what I must do. I am finished with you.||„|
|~ Merlina, as the Dark Queen.|
Merlina is a sorceress and the true main antagonist of Sonic and the Black Knight. She is the granddaughter of the great wizard Merlin. She is also the first main villain Sonic has fought that was female.
Before the events of the game, the illusion of King Arthur created by Merlin (the real King Arthur has been long dead) has become corrupted by the power of the Scabbard of Excalibur, which has turned into Deathcalibur. Merlina wants to overthrow the dark knight and summons the Knight of the Wind, Sonic the Hedgehog. Merlina tells Sonic about Camelot's fate and about how he must find the sword Caliburn and learn to wield it to defeat King Arthur, though she does not tell him about what she plans for Camelot after King Arthur's defeat. After Sonic finds Caliburn and challenges the King, Merlina tells Sonic to meet with the Lady of the Lake and disappears until right before the second battle with Arthur. They have a brief conversation and then go their separate way.
In the Castle of Camelot, Merlina has been cornered by the Knights of the Round Table. Sonic comes in with Deathcalibur, confused about why King Arthur disappeared into a puff of smoke after being killed. Merlina then takes Deathcalibur and reveals that the King that Sonic was fighting was fake. She then used Deathcalibur and her own sorcery to open a portal to the Underworld and begins corrupting Camelot. She creates a shield over the castle, unable to be assaulted. Sonic and the Knights of the Round Table use Caliburn and the Sacred Swords to break the barrier, allowing Sonic to confront Merlina. He asks why she is doing this, and she explains that all things eventually ends, and she wants to use the power of the Underworld to stop death by merging Camelot with the land of darkness. Sonic says that this is unnatural and that all things must end and you should just live your live to the fullest before it is over. Merlina has enough of the talk and transforms into the "Dark Queen", and mercilessly attacks Sonic, breaking Caliburn and nearly killing Sonic. However, Sonic's determination and the power of the Sacred Swords wielded by the Knights caused Caliburn to transform into Excalibur, while Sonic gains golden armor and the ability to fly. Excalibur-Sonic and the Dark Queen do battle, but Excalibur destroys Merlina's dark powers and restores Camelot. Merlina then accepts the fate of the world and everything in it, and ends her reign of darkness.