In Greek mythology, Scylla was a monster that lived on one side of a narrow channel of water, opposite its counterpart Charybdis. The two sides of the strait were within an arrow's range of each other—so close that sailors attempting to avoid Charybdis would pass too close to Scylla and vice versa.

Scylla was a horrible sea monster with four eyes, six long necks equipped with grisly heads, each of which contained three rows of sharp teeth. Her body consisted of twelve tentacle-like legs and a cat's tail and with four to six dog-heads ringing her waist.