Orcus

Orcus, also known as Tenebrous was a demon prince and purported primordial that served as master of the undead from the depths of the Abyss. Returned from undeath but not technically alive, the Demon Lord of Undeath was the multiverse's staunchest advocate for stagnation, seeking to exterminate all life, to darken and desolate all worlds, until all that remained in his static reality were undead moved only by his will. The Blood Lord was believed to be one of the mightiest Demon Lords, one that inspired dread in the hearts of gods. The Shadow That Was was among the powers of the Abyss most often worshiped as deity by the mortals of the Prime Material plane, and even more than the Prince of Demons himself, was close to obtaining true divinity.

I will be the last creature when I am done. The cosmos will then be perfect, free of the braying abominations that are all other living things.
— Orcus

Description

Orcus was the very picture of demonic, an imposing figure of vaguely humanoid form standing some 15 ft (4.6 m) to 20 ft (6.1 m) tall. His frame was immense, a twisted fusion of corpulence, muscle and rot-bloated flesh. His physique was marked by bestial features: the horned, dessicated head of a ram, thick-furred legs and cloven hooves of a goat, massive, black wings of a bat, a great maw filled with tusks, and a long, thick, constantly moving tail, poison-tipped and covered in spines. Foul and hideous, Orcus seemed to walk the line between life and undeath. His wings stirred clouds of reeking, diseased air and his body was riddled with sores, suggesting he was alive, albeit sickly, while his skull-like head, nearly bereft of flesh, and the glowing red eyes within hinted he was undead.