The Comte d'Erlette is a French aristocrat and the author of the "infamous" and "ghastly" Cultes des Goules.
His actual name is Francois-Honore Balfour and his writing of Cultes des Goules is "rather disappointing because its author had possessed more fantasy than knowledge about the hideous things he was writing about. (EXP: "Darkness, My Name Is" Eddy C. Bertin)
Behind the Mythos
The fictional writer is first mentioned in Robert Bloch's 1935 story "The Suicide in the Study". Howard Phillips Lovecraft uses the name in two 1935 stories, "The Shadow Out of Time" and "Haunter of the Dark". Derleth himself refers to d'Erlette in "The Adventure of the Six Silver Spiders" (1950) and "The Black Island" (1952).
In "The Horror in the Gallery", by Lin Carter, it is revealed that the Comte d'Erlette proposed a classification system according to which the Great Old Ones can be divided into four categories, corresponding to the classical four elements (earth, water, air, fire), which are mutually opposed to each other. This references the fact that the real life Derleth invented this same system and used it in his Mythos fiction.