The Call of Cthulhu

A malevolent entity trapped in an underwater city in the South Pacific called R'lyeh. The imprisoned Cthulhu is the source of constant anxiety for mankind at a subconscious level, and also the subject of worship by a number of evil cults. While currently trapped, Cthulhu will eventually return, with worshippers often repeating the phrase "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn" - "In his house at R'lyeh, dead Cthulhu waits dreaming."