Hesiod first names Medusa’s sisters Stheno and Euryale in a surviving literary account. His Theogony gives one of the earliest detailed genealogical descriptions of the Gorgons.
The Theogony presents the Gorgons as daughters of Phorcys and Ceto. Hesiod identifies three sisters: Stheno, Euryale, and Medusa. He also distinguishes Medusa from the other two by making her mortal, while her sisters are deathless.
Homer refers to a Gorgon-like figure, but his poems do not provide the full family account associated with the three named sisters. Later writers, especially Ovid, expanded and reshaped Medusa’s story, including the transformation of her hair into snakes. Hesiod’s genealogy therefore matters because it preserves an early literary framework for the Gorgon family.