In Greek mythology , a nymph and a hunting companion of Artemis .
Though she vowed never to wed, she was seduced by Zeus , who turned her into a she-bear to conceal his infidelity from the jealous Hera . She was then killed by Artemis during a hunt. Other versions hold that it was Artemis or Hera, enraged at her unchastity, who turned her into a bear. After her death Zeus placed her in the heavens as the constellation Ursa Major (Great Bear).