The Gorgons were three sisters: Euryale ("far-roaming"), Stheno ("forceful"), and Medusa ("ruler"). Their origins vary in myth; according to some authors (including Ovid), due to Medusa's disrespect in Athena's temple, the three sisters were turned into terrifying creatures, while Pseudo-Apollodorus and Hesiod opined that the sisters were born, not cursed, and were the children of Phorcys and Ceto, making them sisters of the Graeae amongst others.
Gorgons were a popular image in Greek mythology, appearing in the earliest of written records of Ancient Greek religious beliefs such as those of Homer, which may date to as early as 1194–1184 BC. Because of their legendary and powerful gaze that could turn one to stone, images of the Gorgons were put upon objects and buildings for protection. An image of a Gorgon holds the primary location at the pediment of the temple at Corfu, which is the oldest stone pediment in Greece, and is dated to c. 600 BC.
The concept of the Gorgon is at least as old in classical Greek mythology as Perseus and Zeus. The name is Greek, being derived from "gorgos" and translating as terrible or dreadful. Gorgoneia (figures depicting a Gorgon head, see below) first appear in Greek art at the turn of the eighth century BC. One of the earliest representations is on an electrum staterdiscovered during excavations at Parium. Other early eighth-century examples were found at Tiryns. Going even further back into history, there is a similar image from the Knossospalace, datable to the fifteenth century BC. Marija Gimbutas even argues that "the Gorgon extends back to at least 6000 BC, as a ceramic mask from the Sesklo culture...". In her book, Language of the Goddess, she also identifies the prototype of the Gorgoneion in Neolithic art motifs, especially in anthropomorphic vases and terracotta masks inlaid with gold.
The large Gorgon eyes, as well as Athena's "flashing" eyes, are symbols termed "the divine eyes" by Gimbutas (who did not originate the perception); they appear also in Athena's sacred bird, the owl. They may be represented by spirals, wheels, concentric circles, swastikas, firewheels, and other images. The awkward stance of the gorgon, with arms and legs at angles is closely associated with these symbols as well.
Possibly related, a female figure, probably a sea-goddess is depicted on a Minoan gold ring from the island Mochlos in Crete. The goddess has a monstrous head and she is sitting in a boat. A holy tree is depicted, probably related to the Minoan cult of the tree.
Some Gorgons are shown with broad, round heads, wide mouths, tongues lolling, the tusks of swine, large projecting teeth, flared nostrils and, sometimes, short, coarse beards. In some cruder representations, stylized hair or blood flowing under the severed head of the Gorgon has been mistaken for a beard or wings.
Some reptilian attributes, such as a belt made of snakes and/or snakes emanating from the head or entwined into the hair, as in the temple of Artemis in Corfu, are symbols likely derived from the guardians closely associated with early Greek religious concepts at the centers, such as Delphi where the dragon Delphyne lived and the priestess Pythia delivered oracles. The skin of the dragon was said to be made of impenetrable scales.
While seeking origins, others have suggested examination of some similarities to the Babylonian creature, Humbaba, in the Gilgamesh epic.
A number of early classics scholars interpreted the myth of the Medusa as a quasi-historical, or "sublimated", a memory of an actual invasion.
Medusa, the youngest of the sisters and the only mortal, copulated with Poseidon in Athena's temple. Outraged, Athena changed Medusa into the ugliest monster imaginable. Her gaze could turn anyone she looked upon to stone. Her sisters went to Athena demanding that she turned their sister back, but Athena only turned them into monsters as well.
Medusa was later beheaded by Perseus, with the aid of Hermes and Athena. From the blood of her neck came Pegasus and Chrysaor. As the head retained its power to petrify, Perseus later used the head to defeat Cetus, a sea monster sent by Poseidon to punish Cepheus and Cassiopeia by devouring their daughter Andromeda. It was also used to turn Atlas to stone in an act of mercy, thereby forming the Mountains. He later gave the head of Medusa to Athena, who affixed it to her shield (the Aegis) as a protective ornament, referring to the apotropaiac function of gorgoneia (carvings or engravings of a gorgon's head used to deter evil).