In Greek mythology, Callisto or Kallisto (; Ancient Greek: [kallist:]) was a nymph, or the daughter of King Lycaon; the myth varies in such details. She was one of the followers of Artemis (Diana for the Romans) who attracted Zeus. According to some writers, Zeus transformed himself into the figure of Artemis to lure Callisto and seduce her. She became pregnant and when this was eventually discovered, she was expelled from Artemis's group, after which a furious Hera, the wife of Zeus, transformed her into a bear. Later, just as she was about to be killed by her son when he was hunting, she was set among the stars as Ursa Major ("the Great Bear"). She was the bear-mother of the Arcadians, through her son Arcas by Zeus.
[Callisto] chose to occupy herself with wild-beasts in the mountains together with Artemis, and, when she was seduced by Zeus, continued some time undetected by the goddess, but afterwards, when she was already with child, was seen by her bathing and so discovered. Upon this, the goddess was enraged and changed her into a beast. Thus she became a bear and gave birth to a son called Arkas.
According to Ovid, it was Jupiter who took the form of Diana so that he might evade his wife Juno's detection, forcing himself upon Callisto while she was separated from Diana and the other nymphs. Callisto's subsequent pregnancy was discovered several months later while she was bathing with Diana and her fellow nymphs. Diana became enraged when she saw that Callisto was pregnant and expelled her from the group. Callisto later gave birth to Arcas. Juno then took the opportunity to avenge her wounded pride and transformed the nymph into a bear. Sixteen years later Callisto, still a bear, encountered her son Arcas hunting in the forest. Just as Arcas was about to kill his own mother with his javelin, Jupiter averted the tragedy by placing mother and son amongst the stars as Ursa Major and Minor, respectively. Juno, enraged that her attempt at revenge had been frustrated, appealed to Tethys that the two might never meet her waters, thus providing a poetic explanation for their circumpolar positions in ancient times.
Either Artemis "slew Kallisto with a shot of her silver bow," perhaps urged by the wrath of Juno (Hera) or later Arcas, the eponym of Arcadia, nearly killed his bear-mother, when she had wandered into the forbidden precinct of Zeus. In every case, Zeus placed them both in the sky as the constellations Ursa Major, called Arktos (), the "Bear", by Greeks, and Ursa Minor.
The name Kalliste (), "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 (? ), date before the third century BCE. Artemis Kalliste was worshiped 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 (?) as Arcas, the "Bear-warden" (Arktophylax; ?):
He is Arkas the son of Kallisto and Zeus, and he lived in the country about Lykaion. After Zeus had seduced Kallisto, Lykaon, pretending not to know of the matter, entertained Zeus, as Hesiod says, and set before him on the table the babe [Arkas] which he had cut up.
The stars of Ursa Major were all circumpolar in Athens of 400 BCE, and all but the stars in the Great Bear's left foot were circumpolar in Ovid's Rome, in the first century CE. Now, however, due to the precession of the equinoxes, the feet of the Great Bear constellation do sink below the horizon from Rome and especially from Athens; however, Ursa Minor (Arcas) does remain completely above the horizon, even from latitudes as far south as Honolulu and Hong Kong.
According to Julien d'Huy, who used phylogenetic and statistical tools, the story could be a recent transformation of a Palaeolithic myth.
Callisto's story was sometimes depicted in classical art, where the moment of transformation into a bear was the most popular. From the Renaissance on a series of major history paintings as well as many smaller cabinet paintings and book illustrations, usually called "Diana and Callisto", depicted the traumatic moment of discovery of the pregnancy, as the goddess and her nymphs bathed in a pool, following Ovid's account. The subject's attraction was undoubtedly mainly the opportunity it offered for a group of several females to be shown largely nude.
Titian's Diana and Callisto (1556-1559), was the greatest (though not the first) of these, quickly disseminated by a print by Cornelius Cort. Here, as in most subsequent depictions, Diana points angrily, as Callisto is held by two nymphs, who may be pulling off what little clothing remains on her. Other versions include one by Rubens, and Diana Bathing with her Nymphs with Actaeon and Callisto by Rembrandt, which unusually combines the moment with the arrival of Actaeon. The basic composition is rather unusually consistent. Carlo Ridolfi said there was a version by Giorgione, who died in 1510, though his many attributions to Giorgione of paintings that are now lost are treated with suspicion by scholars. Other, less dramatic, treatments before Titian established his composition are by Palma Vecchio and Dosso Dossi. Annibale Carracci's The Loves of the Gods includes an image of Juno urging Diana to shoot Callisto in ursine form.
Although Ovid places the discovery in the ninth month of Callisto's pregnancy, in paintings she is generally shown with a rather modest bump for late pregnancy. With the Visitation in religious art, this was the leading recurring subject in history painting that required showing pregnancy in art, which Early Modern painters still approached with some caution. In any case, the narrative required that the rest of the group had not previously noticed the pregnancy.
Callisto being seduced by Zeus/Jupiter in disguise was also a popular subject, usually called "Jupiter and Callisto"; it was the clearest common subject with lesbian lovers from classical mythology. The two lovers are usually shown happily embracing in a bower. The violent rape described by Ovid as following Callisto's realization of what is going on is rarely shown. In versions before about 1700 Callisto may show some doubt about what is going on, as in the versions by Rubens. It was especially popular in the 18th century, when depictions were increasingly erotic; François Boucher painted several versions.
Aeschylus' tragedy Callisto is lost.