In Greek mythology, Ixion (/ɪkˈsaɪ.ən/ ik-sy-ən; Greek: Ἰξίων, gen.: Ἰξίωνος) was king of the Lapiths, the most ancient tribe of Thessaly, and a son of Ares, or Leonteus, or Antion and Perimele, or the notorious evildoer Phlegyas, whose name connotes "fiery". Peirithoös was his son (or stepson, if Zeus were his father, as the sky-god claims to Hera in Iliad 14)
Ixion married Dia, a daughter of Deioneus (or Eioneus) and promised his father-in-law a valuable present. However, he did not pay the bride price, so Deioneus stole some of Ixion's horses in retaliation. Ixion concealed his resentment and invited his father-in-law to a feast at Larissa. When Deioneus arrived, Ixion pushed him into a bed of burning coals and wood. These circumstances are secondary to the fact of Ixion's primordial act of murder; it could be accounted for quite differently: in the Greek Anthology (iii.12), among a collection of inscriptions from a temple in Cyzicus is an epigrammatic description of Ixion slaying Phorbas and Polymelos, who had slain his mother, Megara, the "great one".
Ixion went mad, defiled by his act; the neighboring princes were so offended by this act of treachery and violation of xenia that they refused to perform the rituals that would cleanse Ixion of his guilt (see catharsis). Thereafter, Ixion lived as an outlaw and was shunned. By killing his father-in-law, Ixion was reckoned the first man guilty of kin-slaying in Greek mythology. That alone would warrant him a terrible punishment.
However, Zeus had pity on Ixion and brought him to Olympus and introduced him at the table of the gods. Instead of being grateful, Ixion grew lustful for Hera, Zeus's wife, a further violation of guest-host relations. Zeus found out about his intentions and made a cloud in the shape of Hera, which became known as Nephele (nephos "cloud") and tricked Ixion into coupling with it. From the union of Ixion and the false-Hera cloud came Centauros, who mated with the Magnesian mares on Mount Pelion, Pindar told, engendering the race of Centaurs, who are called the Ixionidae from their descent.
Ixion was expelled from Olympus and blasted with a thunderbolt. Zeus ordered Hermes to bind Ixion to a winged fiery wheel that was always spinning. Therefore, Ixion is bound to a burning solar wheel for all eternity, at first spinning across the heavens, but in later myth transferred to Tartarus. Only when Orpheus played his lyre during his trip to the Underworld to rescue Eurydice did it stop for a while.