Graz'zt

The Demon Prince Graz'zt has a complicated history. Originally an Angel in the service of the Mourned God, he took part in Asmodeus' rebellion and was punished along with him, falling and becoming a Devil under the rule of Hell. After countless millenia in the Blood War  , he defected to the service of the Abyss, seizing power as a Demon Prince. He is one of Asmodeus' most hated opponents in the Blood War for his betrayal, as well as a cunning strategist and a ruthless combatant.
According to legend, Graz'zt became the lover of the witch Iggwilv and sired several children with her. This time, however, he was the one betrayed, as she used her bonds with Graz'zt to steal the true names of numerous fiends, possibly including his own, all of which she recorded in the Demonomicon of Iggwilv. Legend says that Graz'zt dares not move against her, as he can't be certain how she would use his true name or those of his officers against him.