Demon

No one is sure exactly what the first demons were. The Abyss was created from a Seed of Evil that Tharizdun planted in the depths of the Elemental Chaos Overview, and some believe that they were a race of foul entities called forth from the Seed named the tanari’i. Some say that they were Primordials and Elementals who fled into the depths of the newborn Abyss rather than be imprisoned by the Gods. Whatever they once were, what they are is chaos and destruction incarnate. They would likely have broken out of the Abyss and wreaked havoc on the rest of the planes by now if not for the constant Blood War waged by Asmodeus and the Devils of Hell.