Dia (Greek: Δία or Δῖα, "heavenly", "divine" or "she who belongs to Zeus"), in ancient Greek religion and folklore, may refer to:
Dia, a goddess venerated at Phlius and Sicyon. She was seen by the locals as identical to Hebe and/or Ganymeda.
Dia, daughter of Deioneus or Eioneus, wife of Ixion (who killed her father so as to not pay the bride price) and with her husband, she became mother of the Lapith Pirithous, whose marriage to Hippodameia was the occasion of the Lapiths' battle with the Centaurs. According to Homer, after having sex with Zeus, who was disguised as a stallion, she gave birth to Pirithous; a folk etymology derived Pirithous' name from περιθεῖν "to run around", because that was what Zeus did to seduce Dia.
Dia, daughter of the king Lycaon (thus sister of Callisto), mother of Dryops by Apollo.
Dia, a daughter of Aeolus.
Dia, daughter of Porthaon and mother of Thersites by Agrius.
Dia, alternate name for Hippodamia the wife of Pirithous (thus daughter-in-law of another Dia).
