Pazuzu

Pazuzu The first and most ancient demon lord is one of the oldest and deplorable of his kind. Also known as the Dark Angel of the Foour Winds he is exceptionally powerful. His dominion is that of all evil flying creatures, even among all the different layers of the Abyss.
He rules on the first layer of the Abyss called Pazunia, known as the Plain of Infinite Portals or the Palace of 1,001 Closets. It is harsh environment with many pits and chasms tore into the surface. The pocks in the surface are portals that lead to other planes of the abyss not only that but they lead to ther planes as well including mortal worlds and Pazuzu knows where each one leads to. In fact he is the only one that knows each and every one.
Pazuzu is not concerned with the conquest of the Abyss like the other demon lords. Instead he gains his pleasures from corruption. Mortals are his target of choice especially the innocent and the honest. It is whispered that he was the one responsible for one of the most prolific coruptions, that of the angel Asmodeus.
It is believed that he is responsible for bringing the Blood War. No one knows for sure but it is said that he is the only demon lord on good terms with the Archdevils of Hell. Ironically he has the ire of the demon lord Graz'zt, who was supposedly a Lord of the Nine Hells before becoming a Demon Prince.