The H.P. Lovecraft Wiki
The H.P. Lovecraft Wiki

The madness and monstrosity lay in the figures in the foreground- for Pickman's morbid art was pre-eminently one of demoniac portraiture. These figures were seldom completely human, but often approached humanity in varying degree. Most of the bodies, while roughly bipedal, had a forward slumping, and a vaguely canine cast. The texture of the majority was a kind of unpleasant rubberiness.
~ HPL, Pickman's Model

This subject contains information from the "Lovecraft Circle" Myth Cycles, and while guided by HPL are not based on his work alone. Ghouls are a species of cannibalistic humanoids featured in several of Lovecraft's works.

They are first depicted in the short story Pickman's Model, where the eponymous main character meets with the beings regularly to paint them in various poses and activities. It is revealed in The Dream-Quest of Unknown Kadath that Pickman is in fact a partial or full-blooded ghoul, and now resides with them in the Dreamlands as a chieftain.

In combat, they are known to use items such as headstones and were unfamiliar with other types of weaponry up until their battle with the Moon-beasts. It was here that they first discovered, and quickly mastered, the use of spears and of javelins. With this newfound technology, they were able to annihilate the garrison of Moon-beasts on the nameless rock off the coast of Sarkomand in the Dreamlands.

On specific planets they worship a number of gods such as Baoht Z'uqqa-mogg (EXP: "Mysterious Manuscripts" RPG Module Thomas M. K. Stratman) or Mordiggian (ADJ: "The Charnel God" Clark Ashton Smith).