Erichthonius (ĕrĕkthō´nēəs), in Greek mythology, son of Hephaestus and Athena, half man and half serpent. After his birth Athena concealed him in a chest that she gave to the daughters of Cecrops to keep. They opened it and were so frightened by Erichthonius' shape that they killed themselves. Athena then reared him among the gods. He is often confused with Erechtheus.