The underworld is a fictional location in the Dream Cycle of H. P. Lovecraft. It is described in detail in Lovecraft's novella The Dream-Quest of Unknown Kadath (1926).
The underworld lies beneath the whole of the Dreamlands and has a few entrances to it in various places. It is dimly lit by a mysterious phosphorescence known as the "death-fire". The underworld is inhabited by a variety of horrors, the most common being the ghouls.
Inhabitants
Ghasts
After a moment something about the size of a small horse hopped out into the grey twilight, and Carter turned sick at the aspect of that...