The Elder Sign is an icon, symbol, or rune in the Cthulhu Mythos, whose stories describe it as a form of protection against evil forces. Although not described in Lovecraft’s work, he illustrated it in correspondence as a line with five branches.
Lovecraft described the Elder Sign only once in his writings, as given by the aged alcoholic Zadok Allen in “The Shadow Over Innsmouth” (1936): “In some places they was little stones strewed about — like charms — with somethin’ on ’em like what ye call a swastika nowadays. Prob’ly them was the Old Ones’ signs.” In this story, the sign is used as a defense against Deep Ones; apparently, the Deep Ones cannot harm someone protected by an Elder Sign. However, Lovecraft is known to have drawn it in at least one of his correspondences as a single line with 5 shorter lines branching off. Mythos writer August Derleth described the Sign as a warped, five-pointed star with a flaming pillar (or eye) in its center, and it is this interpretation which has become the most popular in subsequent Mythos literature.