Necronomicon Sigil of the gateway Silver Goetia Occult Gothic Cthulhu Sigil . Cthulhu Sea Monster Ocean Terror Ocean Monster Mythical Sea Relic Giant Octopus Sigil of the gateway Necklace Cthulhu is a monstrous entity who lies "dead but dreaming" in the city of R'lyeh, a place of non-Euclidean madness presently (and mercifully) sunken below the depths of the Pacific Ocean. Cthulhu appears in various monstrous and demonic forms in early myths of the human race. Racial memory preserves Him as humanity's most basic nightmare. Cthulhu is the high priest of the Great Old Ones, alien beings who ruled the Earth before humanity formed, worshipped as gods by some misguided people.