Pazuzu
Pazuzu is an ancient demon/god originally worshipped/feared in Assyria and Babylon; although feared as a master of "evil wind demons", he was also worshipped. Although this was partially to make him stay his hand when it came to doling out plagues, famine and pestilence, and to fix them when they did happen, it was also because he absolutely hated another demoness, Lamashtu, who caused miscarriages and stillbirths, and so he was a protector of pregnant women. Described as resembling a lion-faced man with four eagle's wings, the claws of a lion/eagle, and the head & body of a snake for a cock, he's most relevant to /tg/ because he was adopted into Dungeons & Dragons as part of the hierarchy of Demon Princes.
As the Demon Prince of Air, Pazuzu technically claims dominion over Torremor, the 503rd Layer of the Abyss, but he acts as though the skies of all 666 layers belong to him, and is most commonly seen roaming the skies of Pazunia, the 1st Layer. Pazuzu belongs to the minority of Demon Princes who favor a more subtle approach to corruption, such as Graz'zt and Fraz-Urb'luu; his favorite trick is using his relative freedom as a Demon Prince to take advantage of a special summoning trick, materializing before anyone who chants his name three times in succession and offering them help, mostly by literally granting their wishes. The first one is always free, but this just acts as bait to lure individuals into summoning him again and again, slowly corrupting themselves to his service. Pazuzu feeds on honesty, innocence and purity, existing only to corrupt others, and thusly considers dicking around with mortals to be far more important than the petty squabbles of his own kind.
Besides cults shaped from his playthings, Pazuzu is most popular with flying monsters, such as harpies, with fiendish variants of such races making up the bulk of his demonic hordes alongside infernal fliers like vrocks and his prize minions, the anzu, which resemble giant four-winged eagles with the heads of lions.
Pazuzu's symbol is a bird's claw decorated with gold or jewels clutching a plucked eyeball, with the tips of its talons just piercing the soft flesh. Pazuzu himself looks like four-winged bird-man, with talons for feet and a needle-toothed beak for a face.
Pazuzu's main rivalry is with Graz'zt, but D&D also acknowledges his enmity for the "obscure" and "weak" Demon Queen of Miscarriage & Monstrous Births, Lamashtu, whom he maimed by eating her eyes before banishing her to some layer of the Abyss. Ironically, in Pathfinder, the relationship is reversed; there, Pazuzu is the weak and comparatively powerless demon, whilst Lamashtu is a full-fledged evil goddess. Possibly because Pathfinder prides itself as being "Grimdark D&D 3.75", so it's more comfortable with a demon queen of such a nature.
Late 3rd edition and 4th edition explained Pazuzu's uncharacteristic scheming nature for a Demon Prince as stemming from the fact he's not a Tanar'ri, but an older and fouler evil entity known as an Obyrith.