Rise of the Demon Lords
Hulking quaggoth who speaks perfect Elvish
This hulking quaggoth is the most menacing-looking prisoner in the slave pen, and the other prisoners give him a wide berth. When spoken to, though, he replies in the most urbane Elvish. He explains that he is not, in fact, a quaggoth at all! Although Derendil usually behaves like a highborn prince, he responds to stress — and particularly threats — like a quaggoth; violently tearing foes limb from limb and rending their flesh with sharp claws and teeth. He comes back to himself when someone reinforces his true identity to snap him out of it. The magic of the curse is slowly destroying his personality.
He is a gold elf polymorphed into a quaggoth by a curse. He calls himself Prince Derendil of the kingdom of Nelrindenvane in the High Forest. His throne was usurped by the evil wizard Terrestor, who trapped him in this form and exiled him from his people.