A Cthulhu Mythos anthology is a type of short story collection that contains stories written in, or related to, the Cthulhu Mythos genre of horror fiction launched by H. P. Lovecraft. Such anthologies have helped to define and popularize the genre.

The Cthulhu Mythos is a mythopoeia and a shared fictional universe, originating in the works of American horror writer H. P. Lovecraft. The term was coined by August Derleth, a contemporary correspondent and protégé of Lovecraft, to identify the settings, tropes, and lore that were employed by Lovecraft and his literary successors. The name "Cthulhu" derives from the central creature in Lovecraft's seminal short story "The Call of Cthulhu", first published in the pulp magazine Weird Tales in 1928.