Cthulhu is a vast Great Old One with an octopus head, dragon wings, and a humanoid body, lying dead-and-not-dead, dreaming, in the sunken city of R’lyeh beneath the Pacific. When the stars are right, it is said, it will wake and end the world.
Even in sleep Cthulhu’s dreams leak into sensitive human minds, sowing madness and vision. It is the most famous being of the Mythos and the archetype of that which "lies dead but dreaming, waiting until the stars come right."