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".