Unaussprechliche Kulte (also known as Nameless Cults or the Black Book) is a fictional book of arcane literature in the Cthulhu Mythos. The book first appeared in Robert E. Howard's 1931 short stories "The Children of the Night" and "The Black Stone" as Nameless Cults. Like the Necronomicon, it was later mentioned in several stories by H. P. Lovecraft.