Yeenoghu

Yeenoghu is a demon lord and the chief being worshiped by gnolls. Dedicated only to destruction, the Ruler of Ruin seeks the collapse of civilization and he will brutally butcher all that stand between him and his rabid slaughter.His demands are simple: kill. Follow his commands, and you shall know blessings beyond your dreams.
Yeenoghu appeara as a gnoll-like creature, 12‒14 ft (3.7‒4.3 m) tall with a grinning skull-like face and a leering pair of burning emerald or amber eyes atop his seemingly emaciated form. A mangy, yellow crest of fur reached from his head to mid-back, with the only hair on his body being small scabby patches. The rest of his body was pale and gray, his leathery hide contrasting with his taut mane and a crest of blackened spines within it. His canine chest is armored with a patchwork of discarded shields and breastplates held together with weighty chains, and decorated with the flayed skin of his enemies. He wields a three-headed flail in his paws.
Yeenoghu's desires are savage in nature, wanting slaughter and destruction above all else. He takes great pleasure in inflicting terror and sorrow before his victims' deaths, destroying treasured possessions and crushing their hopes. He despises civilization and if he were to conquer other realms, abyssal or otherwise, he would not attempt to rebuild their former structures.
To the Beast of Butchery, the gnolls are both his instruments and children, whom he seeks to use to bring his ideal world to fruition. Such a world would be one of endless combat and brutality, where gnolls rule supreme and all other creatures would be either slaves or food. Ultimately when the mortal world possessed one final champion he would challenge them to battle, slay them, and preside victoriously in his version of paradise; a wasteland of decaying corpses, in an absolutely ruined world.
Despite his savage nature, Yeenoghu is not stupid, being capable of subtlety and trickery, but merely choosing not to use it in most circumstances. He actively encourages the arrival of new races into his followers, recognizing the lack of his people's unity. Counting among the Lord of Savagery's favorite demons are barlguras, dretches, hezrous, manes, and especially maw demons and Shoosuvas, all appreciated for their bestial natures. With any entity that did not serve him he will not waste any time on discourse, leaping boldly into battle unless he becomes bored.
Like all demons, Yeenoghu is trapped in the Abyss which is guarded by the devils of Bataar. A few legions of demons escape into Bataar every so often before they are defeated and banished back, but none so far have managed to make it to the other realms, much less Andorra. Because of this Yeenoghu is only able to influence the material realm in smaller ways, usually through his followers.