The Dark Queen (黄泉の女王 Yominojoō?, lit. "Queen of the Underworld"), also called the Queen of the Underworld, is the final boss of Sonic and the Black Knight. It is a transformation of Merlina the Wizard, achieved through the power of scabbard of Excalibur. Merlina assumed this form when she tried to make her kingdom everlasting by applying the scabbard of Excalibur's immortality-granting magic to the world of Camelot, but she was stopped by Excalibur Sonic and Excalibur before she could destroy the world.