In Greek mythology, Pelias was the son of Tire and the god Poseidon or, according to others, the son of the king of Iolkos, Kritheus. He was the twin brother of Nileas and the brother of Aeson. Pelias and Nileas were abandoned during infancy and were raised first by a mare and later by a shepherd. Later, when they grew up, they quarreled for the kingship, but Pelias drove out Nileas, as well as Aeson, and he became king of Iolkos in Thessaly.
One day, Jason, the son of Aeson, arrives in the city of Iolkos, wearing only one sandal, because he had lost the other one when he crossed the city river Anauros. Pelias was afraid that Jason would dethrone him because, according to an oracle, his throne would be in danger from a "single-sandaled". To get rid of him he commissioned Jason to bring the "Golden Fleece" from Colchis and for this reason the famous Argonautic Campaign was organized. Pelias had an inglorious end. He was slaughtered by his daughters at the instigation of Medea, who had returned with Jason to Iolkos, with the aim of obtaining a second life younger, which in the end did not happen. Then Akastos, Pelias’ son, expelled Jason and Medea from Iolkos, seized the throne and organized pan-Hellenic sports competitions in his honor.