The king punished in Tartarus by being tied to a fiery wheel was Ixion.
Ixion was the king of the Lapiths, a people associated with Thessaly. After Zeus granted him purification and welcomed him among the gods, Ixion attempted to violate Hera, Zeus’s wife. Zeus created a cloud in Hera’s shape, often called Nephele, and Ixion was deceived into embracing it.
As punishment, Zeus ordered Hermes to bind Ixion to a winged, fiery wheel that spun without end. In some early traditions the wheel revolved through the heavens; later accounts placed Ixion’s eternal torment in Tartarus, the deepest punitive region of the underworld. The story represents a Greek warning against hubris, betrayal of hospitality, and desire directed toward the divine.
Ixion is easy to confuse with other famous underworld prisoners. Tantalus was denied food and water, Sisyphus repeatedly pushed a boulder uphill, and Tityos was stretched out while vultures consumed his liver. Ixion’s wheel also connects him genealogically to the Centaurs in some versions, through his union with the cloud Nephele.