In Greek mythology, Medusa is a monster who had sharp fangs and hair made of living venomous snakes, that could turn people to stone if they looked at her directly or even indirectly via mirrors or reflections in water (including pools or even something as small as a puddle). Most sources describe her as the daughter of Phorcys and Ceto, though the author Hyginus interposes a generation and gives Meduso/Medea as Phorcys’ parents. Medusa is one of three sisters known as the Gorgons or Graiai.
In most versions of the story, Medusa was a beautiful woman who was raped by Poseidon in Athena’s temple. When Athena saw what Poseidon had done, she transformed Medusa into a monster so that nobody would ever look at her again.
However, there are several different variations of how this name came about: in Hesiod’s Theogony, he states that she was born from Phorcys (a god) and Ceto (a sea monster), along with her sisters Euryale (meaning “farmer’s joy”) and Stheno (meaning “force”).
In one version of the story, Medusa was killed by Perseus using the head of the Hydra as a weapon. In another version of the story, Perseus used his shield as a mirror so that he wouldn’t have to look directly at Medusa while he killed her.