Scylla (Mythology)

Scylla was once a beautiful nymph who was turned into a sea-monster. Scylla made her first appearance in Homer's Odyssey, where Odysseus and his crew encounter her and Charybdis on their travels.

Biography
As a monster she lived on one side of a narrow channel of water, opposite of her 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.

Version 1
Scylla, in Greek mythology, was once a beautiful nymph, but when Poseidon had an affair with Scylla, Amphitrite Halosydne put a potion in the pool where Scylla bathed that turned her into a six-headed monster with a fish tail and dog heads sprouting from her body.

Version 2
Glaucus fell in love with the beautiful nymph Scylla and wanted her for his wife, but she was appalled by his fish-like features and fled onto land when he tried to approach her. He asked the witch Circe for a potion to make Scylla fall in love with him, but Circe fell in love with him instead. She tried to win his heart with her most passionate and loving words, telling him to scorn Scylla and stay with her. But he replied that trees would grow on the ocean floor and seaweed would grow on the highest mountain before he would stop loving Scylla. In her anger, Circe poisoned the pool where Scylla bathed, transforming her into a terrible monster with twelve feet and six heads.

Trivia

 * The strait where Scylla dwelled has been associated with the Strait of Messina between Italy and Sicily. The idiom "between Scylla and Charybdis" has come to mean being forced to choose between two equally dangerous situations.