In Greek mythology, Medusa was one of three Gorgon sisters. These frightful monsters—who lived in the Western Ocean, the frontier of the inhabited world—had large heads with glaring eyes and lolling tongues, snake-entwined hair, tusks, brazen hands, and golden wings. Whoever looked at their hideous faces would instantly turn to stone. Medusa is the most famous Gorgon because of her role in the legend of Perseus.

King Polydektes of Seriphos tricked Perseus into promising the head of Medusa, the only mortal Gorgon, as a wedding gift. With the help of Athena, Hermes, and the nymphs, Perseus flew to the ocean and found the Gorgons asleep. Using a bronze shield as a mirror to avoid her petrifying gaze, he beheaded Medusa. Perseus used Medusa's severed head as a weapon before giving it to Athena for her armor.

According to later tradition, Medusa was originally a beautiful maiden with much-admired hair. After Poseidon seduced her inside the temple of Athena, the goddess punished Medusa by turning her hair into serpents, transforming her into a horrible-looking Gorgon.

The sphinx, a mythological creature with a lion's body and a human head, originated in Egypt and has been known throughout the eastern Mediterranean since the Bronze Age. The Greeks represented the sphinx as a winged lioness with a woman's head. Statues of sphinxes flanked the entrance of tombs or crowned grave markers, guarding against and punishing those who would disturb the dead. On one stele, noted for its polychromy, the sphinxes' femininity is emphasized with necklaces and elaborate diadems worn on long, elegantly coiffed hair.

The most famous sphinx plagued the city of Thebes, devouring anyone who gave the wrong answer to her riddle: what is that which has one voice and yet becomes four-footed, two-footed, and three-footed? Oedipus confronted the sphinx and gave the correct answer—it is man, who crawls as a baby, walks as an adult, and uses a cane in old age. Thus Oedipus forced the sphinx to commit suicide, and saved Thebes.

In Homer's Odyssey, the sorceress Circe warns Odysseus that if he hears the singing of the sirens he will never return home, for they beguile men to their death with the sweetness of their song. As determined by an oracle, the sirens' fate was to live until a mortal survived their deadly call. Odysseus was able to listen to their song by ordering his men to bind him to the mast of his ship, putting wax in their ears, but not his. As a result, the sirens drowned themselves.

Homer does not describe the physical appearance of the sirens, but in Greek art they were represented as hybrid creatures with human heads and the body and claws of a bird of prey. The sirens' appearance, mood, and symbolism changed over time until they resembled mermaids. Their association with the Underworld dates to at least the fifth century B.C., when they were believed to join in mourners' lamentations.

Returning home after the Trojan War, Odysseus and his crew encountered Scylla, a sea monster who, together with Charybdis, a giant whirlpool, terrorized sailors. Homer tells us that Scylla had twelve legs and six long necks with ghastly heads. Yelping like a puppy (skylax), she snatched sailors from ships passing her fog-bound cave and devoured them.

In his Metamorphoses, the Roman poet Ovid relates how Scylla was once a beautiful maiden whose bathing pool was poisoned by the envious sorceress Circe, transforming her waist and groin into a pack of snarling dogs. Scylla was stripped of her sexuality and condemned to a life of solitude, sending countless seafarers to their watery deaths.

Scylla is typically depicted as a beautiful maiden from the waist up, but with dogs and fishtails where her legs would be.