Demogorgon, even claiming the title of Prince of Demons, is one of the most powerful tanar'ri. Its appearance is a pure representation of chaos and madness - a reptilian lower body with a huge forked tail, forked tentacles in place of its forelimbs and twin baboon heads above its shoulders. Its gaze alone is enough to turn its enemies to madness.
It is the Imprisoned One in Watcher's Keep. It can summon demons from the Abyss to aid him and is arguably the most powerful boss in Bhaalspawn saga games.