Medusa is a well-known figure in Greek mythology who is perhaps most famous for her ability to turn men to stone and her hair made from snakes, which are often described as hissing entities with their own minds, rather than simple hair ornaments. As one might imagine, many people view her as a monster, and she was not the sort of creature one wanted to encounter, for obvious reasons. The Greek hero Perseus ultimately defeated Medusa by cutting off her head, using her reflection as a guide for his sword.
The myth has evolved greatly over the centuries. It is generally agreed that her parents were Phorcys and Ceto, and she had two sisters; the three sisters were collectively known as the Gorgons. Medusa, however, did not start out hideous. She was allegedly quite beautiful, and in many myths, she is described as a fresh-faced fair maiden, until she was violated by Poseidon in a temple of Athena.
Athena was so angered by this that she punished Medusa by turning her into a horrifying monster, with hair made from snakes and the ability to turn onlookers into stone. Her name, incidentally, translates as “one who rules over,” or “protectress.” Her face often appears on talismans that are meant to protect people from evil by turning the evil away; such talismans are known as apotropes.
Various versions of her history state that she was pregnant when killed by Perseus, and perhaps even asleep. In any case, Perseus had help; Hermes and Athena helped him figure out how to kill the infamous Gorgon, and as a payment, Perseus brought her head to Athena, who used it as an ornament on her shield.
In some stories, Medusa's blood served as the seed of Pegasus, the winged horse god of Greek mythology. Her blood also apparently gave birth to all of the venomous snakes in Africa, and in some tales, it was transformed into a powerful medicine with the ability to wake the dead. She lives on, however, as an image of terrible womanhood, and in some parts of the West, angry women are described as Gorgons or Medusas.