Denam Morne originally encounters Beelzebuth on the 22nd floor of the Palace of the Dead. She is involved in research on the dark power contained in the Palace, and during several encounters, she shows the player how to use Books of the Dead and Rings of the Dead.
Beelzebuth appears as a young woman--a Siren--but little is known of her, except that she is not human and claims to have possessed her current body. She was known to associate with Georges, although the nature of their relationship is unknown.
The Warren Report states that she was thought to have been a guardian of the Palace, "as she was conversant with the forces of chaos, and liches and other undead did her bidding."
Beelzebuth encountered Denam on floors 22, 41, and 74. Her current body was destroyed during the battle on 74.
Beelzebuth is an archaic variant of the name Beelzebub, which literally means "Lord of the Flies." The name is assigned to numerous entities in Judaeo-Christian literature.
Beelzbute was, presumably, the result of a phonetic translation without knowledge of the intended reference.