A Dark OneEdit
Cthulhu is one of the Dark Ones who once ruled the earth millennia before mankind came into existence. He, along with the other Dark Ones, was imprisoned in the mirror dimension by the first Chosen One. Cthulhu, along with the other Dark Ones, is a master of the Deadites.
Cthulhu is one of the few Dark Ones to have a commonly accepted corporeal image. It was originally described as looking like "...A mixture of human, dragon and octopus..." and is often represented as such.