Yeenoghu
Yeenoghu is demon lord of slaughter and lord of gnolls. He ruled over the Death Dells, a layer of the Abyss.
History
Yeenoghu brought Ehbony Blackpaw and two other gnolls I don't remember the names of from the Blackpaw pack to the Death Dells to serve as his champions. Yrych Blackpaw denied this offer.
Later, he was present when gnolls in his layer killed Aela Stormcaller.
Yeenoghu would later meet Showtime and make a deal with them, giving them the leaders of Proxima's Nightmare as prisoners and allowing the Galactic Conclave to leave the planet in exchange for Showtime capturing a shield generator for him and leaving the planet for him to conquer. While the party honored this deal, Scaid Zeppallusipphir deactivated the shield generator, causing Yeenoghu to flip shit and declare war on the Conclave. In addition, Yeenoghu made a separate deal with Arda, granting her some demonic power in exchange for her doing his bidding.