In Greek mythology, Callisto or Kallisto (/kəˈlɪstoʊ/; Greek: Καλλιστώ [kallisˈtɔː]) was a nymph, or the daughter of King Lycaon, based on conflicting accounts of the myth. Transformed into a bear and set among the stars, she was the bear-mother of the Arcadians, through her son Arcas.
The fourth Galilean moon of Jupiter is named after Callisto.
The name Kalliste (Καλλίστη), "most beautiful", may be recognized as an epithet of the goddess herself, though none of the inscriptions at Athens that record priests of Artemis Kalliste (Άρτεμις Καλλίστη), date before the third century BCE. Artemis Kalliste was worshipped in Athens in a shrine which lay outside the Dipylon gate, by the side of the road to the Academy. W. S. Ferguson suggested that Artemis Soteira and Artemis Kalliste were joined in a common cult administered by a single priest. The bearlike character of Artemis herself was a feature of the Brauronia.
The myth in Catasterismi may be derived from the fact that a set of constellations appear close together in the sky, in and near the Zodiac sign of Libra, namely Ursa Minor, Ursa Major, Boötes, and Virgo. The constellation Boötes, was explicitly identified in the Hesiodic Astronomia (Αστρονομία) as Arcas, the "Bear-warden" (Arktophylax; Αρκτοφύλαξ):