Isis (Īˈsĭs) [key], nature goddess whose worship, originating in ancient Egypt, gradually extended throughout the lands of the Mediterranean world during the Hellenistic period and became one of the chief religions of the Roman Empire. The worship of Isis, combined with that of her brother and husband Osiris and their son Horus, was enormously resistant to the influence of early Christian teachings, and her mysteries, celebrating the death and resurrection of Osiris, were performed as late as the 6th cent. A.D. The functions of many goddesses were attributed to her, so that eventually she became the prototype of the beneficent mother goddess, the bringer of fertility and consolation to all. She was the daughter of the sky goddess Nut and the earth god Geb. Her symbol was a throne and later the cow, and she was frequently represented with a cow's head or cow's horns. During the Hellenistic period, her image outside Egypt became increasingly Hellenic, with ideal features and locks framing her face. Isis was also a goddess of magic, and legends tell of her ability to counteract evil by casting spells.
See R. E. Witt, Isis in the Greco-Roman World (1981).