There was one thing called “The Lesson”—heaven pity me, that I ever saw it! Listen—can you fancy a squatting circle of nameless dog-like things in a churchyard teaching a small child how to feed like themselves? The price of a changeling, I suppose—you know the old myth about how the weird people leave their spawn in cradles in exchange for the human babes they steal. Pickman was shewing what happens to those stolen babes—how they grow up—and then I began to see a hideous relationship in the faces of the human and non-human figures. He was, in all his gradations of morbidity between the frankly non-human and the degradedly human, establishing a sardonic linkage and evolution. The dog-things were developed from mortals!
— Pickman’s Model, H.P. Lovecraft
Surpassed only by the Deep Ones among Call of Cthulhu RPG minions, Ghouls are truly a Keeper favorite. When the Investigators dare to get on a boat, or shamble through the mid-morning mist of Innsmouth, send a Deep One. When the Investigators go skulking around subterranean caverns, or prowling around cemeteries at night, well, a slavering pack of Ghouls cannot be far behind.
These creatures originate in Arabic folklore where they are called ghūls. Ghouls dwell in burial grounds, and are eaters of the dead, a trait which they maintain throughout western fiction and roleplaying games, including the Lovecraft mythos. In Arabic folklore, they are sons of Iblis, the chief of the evil Jinni. In Lovecraft’s fiction, their origin is perhaps even more sinister, for they, as the quote above describes, are humans twisted and mutated by some dark and ancient means, known only to ghoul-kind.
I like to recommend Pickman’s Model to first time reader’s of Lovecraft’s stories for two reasons: it is short, and it gives all of the creeping dread that is so emblematic of Lovecraft’s fiction. And, like The Outsider, it has a bit of a twist at the end, one whose horror is not at all diminished if you happen to see it coming.