"Hard Knight's Day" is a 1987 episode of American animated series The Real Ghostbusters that employs elements from Arthurian legend.
Plot[]
Ghostbuster Peter Venkman and his date Doris Tibbs go to the Cloisters museum in New York, where the Genevieve Tapestry is being exhibited. The brutal Bruce Sans Pitie then emerges from a painting he was put into by Merlin's curse, with his knights also revived to aid him, plus other paintings come to life. He believes Doris is Genevieve, whom he loved, and she slowly starts to turn into Genevieve herself. The rest of the Ghostbusters team soon come on the scene to help Peter against the spectral Bruce, but they discover that their beams will be unable to hold him until daytime comes and he is weakened. So the team sets out to distract him until the time is right, with some unicorns lending a hoof.