H. P. Lovecraft and many of his associates were great admirers of Chambers' book of short stories, and incorporated many of his characters and symbols into their own works. In the Cthulhu Mythos, developed by Lovecraft and his associates, a yellow sign is the sign of Hastur, one of whose avatars is the King in Yellowness, & is utilized by members of Hastur's cult to identify each more. These are virtually all normally believed to exist as similar inside appearance to the yellow triskele (3-armed hakenkreuz), even representing tentacles, since Hastur himself is typically described as an aquatic animal by having tentacles. Yet, there are likewise more symbols which are then claimed to exist as a sign.

Around Robert Shea and Robert Anton Wilson's Illuminatus!, the Cult of the Yellow Sign is offered to a single detective as a concocted explanation of human being history. Purportedly, a Cult worships Cthulhoid able called lloigor, commits human sacrifice, and has strived throughout history to suppress rationalism. A Cult is opposed per rationalist Illuminati.