(d. 370 BC)
Ruler of Thessaly,
who was the son of the tyrant of Pherai (just north of Volos).
When his father died in 380 BC he succeeded him, and took control of the whole
of Thessaly with his 6000 mercenaries. The situation in Thessaly was then
infested with constant battles between the various aristocratic families of
the area, and Jason found support from Athens and Thebes.
When Thebes had defeated the Spartans at the battle of Leuctra Jason intermediated so that the Spartan army could go home. He wanted to create a state of hegemony in Greece, and had the strongest military power of his time, with 20 000 foot soldiers and a cavalry of 8000. He also built a fleet and planned a pan-Hellenic attack on the Persians.
In 370 BC he wanted to lead the Pythian Games but a group of young Thessalian aristocrats murdered him. Philip II of Macedonia was to continue his plans.