Morcalavin is the main antagonist of the video game Heretic II. He is an ancient Seraph who tries using the seven Tomes of Power, but uses a false one, as the protagonist, Corvus, has one of them. This had made him go insane and create a plague that has swept up the land of Parthoris, making anyone whom it doesn't kill insane.

While Corvus and Morcalavin battle at the end, Corvus switches the false tome for his real one, curing Morcalavin's insanity and ending the plague.