"Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn".
-In his house at R'lyeh, Dead Cthulhu lies dreaming.

Cthulhu is the god-emperor of the Star-Spawn, a race of Great Old Ones (antedelluvian, immortal, semi-invincible and semi-corporeal godlike aliens) from the writings of HP_Lovecraft. He is both the largest and oldest of the race. He is a cousin to Yog-Sothoth, the cheifitan god of the Lovecraftian pantheon.

Cthulhu resembles a bloated humanoid with thick, clawed hands, an octopoid head, and batlike wings. He can be depicted with anywhere from two to six eyes.

Cthulhu led his followers to Earth in aeons past, when the Great Race of Yith and the Mi-Go had run of it, and nurtured, very slightly, the evolution of humanity. It is said that once the stars are right, he will arise from his tomb at R'lyeh, and awaken his star-spawn followers to strip the Earth of humanity-except for his worshippers, whom he will uplift into something close to the Elder Races: free and wild, reveling and killing in joy.

Cthulhu is not his true name, but the closest that mortal speaking organs can come to it.