Jāson (Iāsōn)1. In Greek myth, son of Aeson and leader of the Argonauts.
2. Jason of Pherae, tyrant (c.385–370 BC) of the Greek Thessalian town of Pherae who sought control over the whole of Thessaly; he achieved his object in 374, winning over the last important city, Pharsalus, by diplomacy. Ancient sources have suggested that he may have aimed at becoming the dominant power in Greece and even at leading a Greek expedition against Persia. In 370 he alarmed Greece by his plan to display the strength of his army at the next Pythian festival, and to preside at the games, but he was assassinated before he could carry out his plans and his further intentions remain unknown.
