"Cthulhu Mythos" is the fictional folklore created by author H.P. Lovecraft about a race of ageless creatures known as the "Great Old Ones." Based on scattered descriptions in Lovecraft's short stories, the character Cthulhu is described as a winged anthropomorphic beast with the head of an octopus and some serpentine features. Cthulhu, along with the other Great Old Ones, lies trapped in an ancient city beneath the Pacific Ocean.
Lovecraft introduced Cthulhu in 1926 in the short story "The Call of Cthulhu," in which an earthquake brings the creature's watery prison closer to the surface, allowing him to communicate with a group of humans through visions and dreams. The stories tell of a war between the Great Old Ones and another ancient race as well as Cthulhu's ambitions to regain control of the world. Lovecraft also wrote about a ritualistic cult of humans who worship Cthulhu and work to restore his power.
"Cthulhu Mythos" has flourished far beyond Lovecraft's original works, becoming a pop culture staple and inspiring a cult following in literature, games, TV and film. Many of Lovecraft's contemporaries penned companion stories set in the fictional world of Cthulhu, expanding the pantheon of mythological characters. Other well-known characters include Dagon, a deity who sired half-man, half-fish creatures and Shoggoths, a race of shapeshifters created to work as slaves.