Johannes Klosterheim, often known simply as Klosterheim, is an undead priest. He is a former servant of Lucifer, but has left his service due to Lucifer's desire to be reconciled with God. Klosterheim is an ally of Gaynor the Damned, and an enemy of the Eternal Champion. He has antagonized Graf Ulrich Von Bek, Ulric Von Bek, Oona Von Bek, and even Elric of Melniboné.
Klosterheim is described as a pale, skeletal priest in a black longcoat, with a wide-brimmed black hat.