Callisto was either a nymph or a princess from Arcadia, the daughter of the impious king Lycaon. She was a huntress and one of the chaste companions of Artemis, the goddess of the wild.
Callisto was seduced (or raped) by Zeus, who first approached her disguised as Artemis (or Apollo). When Callisto’s pregnancy was discovered, she was transformed into a bear by either Artemis or Hera—or, in one version, by Zeus himself. Callisto eventually gave birth to Arcas, who became the ancestor of the Arcadians.
In the end, Callisto was either shot by an arrow from Artemis or transformed into Ursa Major, the constellation of the Great Bear. According to some accounts, she was turned into a constellation to save her from her own son Arcas, who failed to recognize his mother while he was hunting in the woods.
Ovid’s retelling of Callisto’s myth eventually became the standard account, though a dizzying array of variants exists, too. The myth was quite popular in ancient literature and art and likely had some connection with the worship of Artemis. In the modern period, Callisto is still remembered as a symbol of the carelessness and cruelty of the gods.