Pazuzu was the winged demon prince of the Infernal Legions during the Chaos Wars at Nishnatoba. Khalas, the Wanderer, of the Triumvirate, discovered his existence, and appeared during the great battle of the Gods to route the Elder Gods. When the Triumvirate's traitorous plans failed, the Tribunal banished Pazuzu to the Chaos Plane, where he remained for some time, until an uprising within the plane saw him weakened and cast out.
Shortly after his arrival in the Chaos Plane, Pazuzu, Slith, and their Inferno Legions expressed alarm as their environment received the brunt of the chaos dispersed by Ayar and began to warp and mutate, creating chaos thralls - among them, Jy'Barrak Golgotha. Eventually, Pazuzu's arrogance and oversight let Golgotha stage a successful coup d'état, swaying even Danaeus, Pazuzu's chief advisor, to his cause. By Golgotha's command, Pazuzu, Slith, and Slith's chief advisor Zsarachnor were exiled to the Prime Material Plane.
While on the Chaos Plane, Pazuzu was summoned by the arcane rituals of the Tsol'teth lords Agith'maal, Terrin'ukia, and Gattan'lier. The demon prince appeared only briefly, much to the Tsol'teth lords' chagrin, and uttered only the word, "Seleucar", before vanishing once more into the ether.
Pazuzu has not been seen or heard from since his exile to the Prime Material Plane. However, it is rumoured by some that he lurks yet in this day and age, under an assumed identity. Those who would venture such theories admit that there is probably more to his tale than meets the eye.