Scylla in Greek mythology, a female sea monster who devoured sailors when they tried to navigate the narrow channel between her cave and the whirlpool Charybdis. In later legend Scylla was a dangerous rock, located on the Italian side of the Strait of Messina. To be between Scylla and Charybdis is to be between two dangers or pitfalls, as between the cave of the sea-monster and the whirlpool.

Scylla was also the name of the daughter of king Nisus of Megara, who betrayed her father and his city to Minos of Crete, and who was drowned in punishment.

Scylla In Greek mythology, a female sea monster. Once a beautiful nymph beloved of Poseidon, Circe changed Scylla into a long-necked, six-headed beast. She lived with Charybdis beside the Straits of Messina between Sicily and Italy and devoured sailors.