In Greek mythology, Mestra (, Mēstra) was a daughter of Erysichthon of Thessaly. Antoninus Liberalis called Mestra as Hypermestra while Erysichthon as Aethon.

Mestra had the ability to change her shape at will, a gift of her lover Poseidon according to Ovid. Erysichthon exploited this gift in order to sate the insatiable hunger with which he had been cursed by Demeter for violating a grove sacred to the goddess. The father would repeatedly sell his daughter to suitors for the bride prices they would pay, only to have the girl return home to her father in the form of various animals. Mestra's great-granduncle Sisyphus also hoped to win her as a bride for his son Glaucus although that marriage did not take place. According to Ovid, Mestra married the thief Autolycus.