Cthulhu in his Kingdom: R'lyeh (Credits: Dominique Signoret)

Cthulhu is a fictional creature created by American writer Howard Phillips Lovecraft.

It is a semi-divine being of prodigious proportions and strength who resides in the lost city of R'lyeh, in a deathlike slumber, awaiting a favorable astral conjunction to awaken him. In the stories of the so-called Cthulhu Mythos, also known as the Cthulhu Mythos (a posthumous definition of Lovecraft's work and additions by many other writers), the author and his followers defined it as a blasphemous deity, worshipped by degenerate, savage, and mad populations, connected to the onset of nightmares, and whose cult involves atrocious human sacrifices. Cthulhu first appears in the story "The Call of Cthulhu" (1928).

Cthulhu is part of the complex mythology created by H. P. Lovecraft, which he attributed to a fictional manuscript (pseudo-biblium) known as the Necronomicon, compiled by the "mad Arab" Abdul Alhazred. Cthulhu is the chief priest of the Great Old Ones, abominable alien creatures who settled on Earth when life on Earth was still in its infancy. He arrived on Earth with his stellar offspring (the so-called "star-spawn of Cthulhu") and founded the legendary city of R'lyeh, where he was imprisoned (whether voluntarily or involuntarily) when the stars aligned correctly ("the stars come right").