The Call of Cthulhu is a short story written by H. P. Lovecraft during the summer of 1926. Written in documentary style, it contains three narratives that are discovered as notes left by a deceased relative. While Cthulhu is a character, it's only hinted at: it is the lord of R'lyeh, an ancient being from the depths of space that came hundreds of millions of years ago to destroy the elder beings of our world. It is described as "a monster of vaguely anthropoid outline, but with an octopus-like head whose face was a mass of feelers, a scaly, rubbery-looking body, prodigious claws on hind and fore feet, and long, narrow wings behind."
The main plot of the story follows several characters as they try to uncover the cryptic nature of the Cthulhu cult, which is discovered amidst a frenzy of worldwide hysteria. Several adventurous characters travel the globe searching out the cult in an attempt to stop them from releasing the dreaded monster from the stars.