The Demogorgon

Birthed from the corpse of a dead god, the Demogorgon is a massive two-headed ape-like creature with lengthy tentacles for arms. It is one of the most powerful demons on record at the Royal Academy, and is known to reside in the Abyss, a hostile section of Kindevion's Underdark. It seems to enjoy striking fear into its victims before going for the kill, and has been known to chase its targets over great distances. It is considered to be, in many respects, unkillable.