Pelias was the King of IoIcus.
Pelias (/ˈpiːliæs/; Ancient Greek: Πελίας) was king of Iolcus in Greek mythology. The son of Tyro and the god Poseidon, he was the one who sent Jason on the quest for the Golden Fleece.
Many years later, Pelias offered a sacrifice by the sea in honor of Poseidon. Jason, who was summoned with many others to take part in the sacrifice, lost one of his sandals in the flooded river Anaurus while rushing to Iolcus. In Virgil's Aeneid and Hyginus' Fabulae (13), Hera/Juno disguised herself as an old woman, whom Jason helped across the river when he lost his sandal.
When Jason and Medea returned, Pelias still refused to give up his throne. Medea conspired to have Pelias' own daughters (the Peliades) kill him. She told them she could turn an old ram into a young ram by cutting up the old ram and boiling it. During the demonstration, a live, young ram jumped out of the pot. Excited, the girls cut their father into pieces and threw them into a pot, in the expectation that he would emerge rejuvenated. Pelias, of course, did not survive.