Demons

The Demons are creatures that, for as big of an impact as they have had in the material plane, not that much is known about them. General knowledge of scholars is that Demons are creatures native to the Abyss, there are specific appearances that demons generally have which show their power, and they are immortal unless killed in their native plane. Other than that, it is known that the most powerful type of Demon are the Demon Lords, which control legions of demons and effect the way those demons look and act, as well as their goals. The deeper into the layers of the Abyss one goes, the more powerful the demons there are, with the most powerful demon known being the Demogorgon. How demons change their appearance as their power grows is a mystery, as well as how one becomes a Demon Lord.