Graz'zt

"We use a most unfortunate idiom when we say of a lustful man prowling the streets that he 'wants a woman.' Strictly speaking, a woman is just what he does not want. He wants a particular pleasure for which a woman happens to be the necessary piece of apparatus. "

– C.S. Lewis

Graz'zt is one of the most iconic Demon Princes from Dungeons & Dragons. Having appeared in every single edition since 1975(!), he is amongst the most powerful of the Demon Princes, and one of the few legitimate contenders for the throne of Demogorgon.

Graz'zt appears as a towering, surprisingly handsome human male with ebony-black skin, tiny horns on his head, yellow eyes, six fingers on each hand, and goat-like legs. He is known for his incredible lust, having a vast harem of humanoids and monsters - including, but not limited to, succubi, harpies, mariliths, and lamias, and being father of an enormous and sprawling family tree of cambions and tieflings.

Per Lost Caverns of Tsojcanth, his most infamous relationship is with the scourge of Perrenland, Iggwilv - especially after she was ruled female. Post-1975 editions have ultimately admitted that Grazzy <3 Iggy were genuinely in love with each other, but too fucked up to admit it or show it in any way that's healthy. From The Ashes adds that through her, he is the father of Iuz.

Graz'zt is also known for being the most patient, cunning and subtle of all Demon Princes - in fact, many would argue that he acts more like an Archdevil than a Demon Prince. 4e actually took this to the logical conclusion and stated that's exactly what he is, asserting that he used to be a Duke of Baator who was sent to wage war on the Abyss, but who betrayed Asmodeus by deciding he'd rather carve out a kingdom of his own than keep working for somebody else.

This Demon Prince's domain Azzagrat actually spans three distinct planar layers (#45-7 if we're counting), the most of any of them. His capital city Zelatar can exist on all three layers simultaneously. He's cunning enough to keep his demons in line over there, so visitors can trade (their soooouls!) with him in peace.

He has a massive, iconic dick greatsword, the Wave of Sorrow, which he wields one-handed like a boss. It deals acid damage. If you cast a frost spell at it, it becomes a dagger. He also has a pile of spells to rely on.

Something not a lot of people know is that Graz'zt (once his sexing of Iggwilv was outed) is based on Satan - specifically, on stories from the British witch trials, where witches would often claim to copulate with Satan (or at least one of his demons) in the guise of a handsome black-skinned man.