Tartarus

In Greek mythology, Tartarus was the lowest point of the universe, below the underworld but separate from it. Tartarus is best known from Hesiod's Theogony as one of the first beings to come into existence in the universe and also as the place of entombment for the monsters, the Titans, and in later myths, for mortals who committed unforgivable sins. The punishments for each mortal was different and depended on the crime they committed. Although, as a deity, he is the father of Typhon, Tartarus is not depicted any other way than a dark abyss used as a prison, therefore there are not many myths or stories of the primordial god.