Ixion was king of the Lapiths, the most ancient tribe of Thessaly. After murdering his father-in-law he was purified by Zeus and brought to Olympus, where he lusted after Hera. Zeus fashioned a cloud in her likeness (Nephele); from their union came Centaurus, progenitor of the centaurs. For this hubris Ixion was bound to a winged fiery wheel that spins forever — at first across the heavens, later in Tartarus.
Adapted from Wikipedia, "Ixion" · CC BY-SA 4.0
I.Family
Ixion's father is variously named — Ares, Leonteus, Antion, or the notorious Phlegyas — and his mother Perimele. He married Dia, daughter of Deioneus, and was reckoned the father (or, in Homer's Zeus-claim, the stepfather) of Peirithous, the Lapith king who later fought the centaurs.
From his union with the cloud Nephele came Centaurus (or Imbros), who mated with the Magnesian mares on Mount Pelion and engendered the race of Centaurs — sometimes called the Ixionidae from that descent.
II.Kin-slaying and exile
Ixion promised Deioneus a bride-price and then failed to pay it; when Deioneus seized some of Ixion's horses in retaliation, Ixion invited him to a feast at Larissa and pushed him into a concealed pit of burning coals. By killing his father-in-law he was reckoned the first man guilty of kin-slaying in Greek mythology, and a violator of xenia (guest-friendship).
Defiled by the act he went mad; neighbouring princes refused the rites that would cleanse him. Zeus alone took pity, purified him, and brought him to the table of the gods on Olympus.
III.Nephele and the Centaurs
Instead of gratitude Ixion grew lustful for Hera. Zeus discovered the intention and shaped a cloud in Hera's likeness — Nephele (from nephos, "cloud") — with which Ixion coupled. From that union came Centaurus, and through him the wild centaur brood of Pelion.
The episode compounds guest-host violation with hubris against the queen of the gods. Pindar's Second Pythian Ode expands the example as a warning against thankless insolence toward divine benefactors.
IV.Punishment on the wheel
Ixion was expelled from Olympus and blasted with a thunderbolt. Zeus ordered Hermes to bind him to a winged fiery wheel that spun without cease — at first across the heavens, in later myth transferred to Tartarus. Pindar is careful to mention the feathers of the wheel; Roman poets and frescoes (notably at the House of the Vettii in Pompeii) keep the bound king as a stock image of underworld torment.
Only when Orpheus played his lyre in the Underworld, seeking Eurydice, did the wheel briefly stop. The Etruscans knew the figure too: an engraved mirror of the mid-fifth century BC shows him bound to an eight-spoked winged wheel.
V.In tragedy and analysis
Aeschylus, Sophocles, Euripides, and Timasitheus each wrote a tragedy of Ixion; none of those plays survives. Modern mythographers have noted the odd joints of the story and proposed aetiological roots — including, with Martin Nilsson, a connection to rain-making magic in which the first officiant's blasphemy becomes the warning built into the tale.