One of the Gorgons, and the only one who was mortal. Her gaze could turn whoever she looked upon to stone. There is a particular myth in which Medusa was originally a beautiful maiden. She desecrated Athena's temple by lying there with Poseidon. Outraged, Athena turned Medusa's hair into living snakes.
Medusa was killed by the hero Perseus with the help of Athena and Hermes. He killed her by cutting of her head and gave it to Athena, who placed it in the center of her Aegis, which she wore over her breastplate.
From Medusa's dead body the giant Chrysaor and the winged horse Pegasus, her son by Poseidon, sprang forth.
From Bullfinch's Mythology:
Many later images of Medusa thwart our expectations of what she should look like. From the previous story, we are led to believe that she was a creature so hideous in appearance that her very glance could petrify the viewer. However, in works such as the Medusa Rondanini, Medusa has the face of a beautiful woman. It is only her expression of deep sorrow -- and the intertwined snakes around her head -- that hint that this is a representation of the monster of myth and legend. This manner of depiction reveals that Medusa was originally a lovely woman -- it was her tragedy that she was foolish enough to compare herself to a goddess.
A Medusa Head in Rome [from The Temple of Hecate]
Robert Graves (Greek Myths, 1958) believes that the myth of Perseus preserves the memory of the conflicts which occurred between men and women in the transition from a matriarchal to a patriarchal society. In fact the function of the Gorgon's mask was to keep men at a safe distance from the sacred ceremonies and mysteries reserved for women, i.e. those which celebrated the Triple Goddess, the Moon. Graves reminds us that the Orphic poems referred to the full moon as the 'Gorgon's head'. The mask was also worn by young maidens to ward off male lust. The episode of Perseus' victory over Medusa represents the end of female ascendancy and the taking over of the temples by men, who had become the masters of the divine which Medusa's head had concealed from them.
Although it may have become less intense, the battle of the sexes was not resolved. The feminine continued to remain a source of fear for men, and the association of women with Medusa, evoked an aspect of the sex which was both fascinating and dangerous. Medusa often appeared in Renaissance poetry, e.g. Ronsard's Second Livre des Amours (S. 79, 1555), but the stare which turned men to stone was often only a conventional metaphor for the lover's 'coup de foudre'. The comparison took on a deeper meaning during the nineteenth century. Baudelaire's Les Fleurs du Mal (1857) and 'decadent' literature such as Lorrain's M. de Phocas (1901), provide illustrations of the dangerous fascination exerted by woman, with her deadly stare and mysterious hair. But it was Goethe's Faust Part I (1808) which supplied the real significance of this connection. During the 'Walpurgis night,' Faust thinks he sees Margarita but Mephistopheles warns him that it is Medusa and explains that 'magic deludes every man into believing that he has found his beloved in her'.
This terrible woman, the paragon of all women, whom every man simultaneously fears and seeks and for whom Medusa is the mask, is in fact the mother, i.e. the great Goddess Mother whose rites were concealed by the Gorgon's face. Countless texts illustrate Medusa's affinity with the depths of the sea and the terrible power of nature, e.g. Hugo's Les Travailleurs de la Mer (1864), Lautrémont's Chants de Maldoror (1869) and Pierre Louÿs' Aphrodite (1896), but the most explicit example is probably the text written by Freud in 1922: Das Medusenhaupt -- 'Medusa's Head'. He presents her as the supreme talisman who provides the image of castration -- associated in the child's mind with the discovery of maternal sexuality -- and its denial. The snakes are multiple phalluses and petrifaction represents the comforting erection.
Hmmmm. I wonder if there's anything to this notion of Medusa embodying the disconcerting strangeness of the feminine...
When the bare eyes were before me
And the hissing hair,
Held up at a window, seen through a door.
The stiff bald eyes, the serpents on the forehead
Formed in the air.
[from "Medusa" by Louise Bogan]
[Drawing from The Medusa Picture]
...Guess not. Well, like most myths, Medusa's been absorbed by popular culture and commodified. She's now server architecture, a Linux kernal patch, a film distribution hub, a pyrotechnics company, a hotel in Australia, an art gallery in Greece, a dance club in Seattle, a music festival at CBGB's, and, of course...
How many Greek heroes does it take to change a Gorgon's light bulb?