Themisto may refer to:

Greek mythology

• Themisto, the third and last wife of Athamas
• Themisto (mythology), various figures including:
  • Themisto, a daughter of the river god Inachus, who became the mother of Arcas by Zeus
  • Themisto, one of the Nereids
  • Themisto, daughter of the Hyperborean king Zabius, mother of Galeos by Apollo

Other meanings

• Themisto (moon) of Jupiter
• Themisto (crustacean), a genus of amphipod crustaceans