Io, << EYE oh >>, in Greek mythology, was a mistress of the god Zeus. Soon after Zeus became the ruler of the universe, Io was changed into a beautiful white cow. One myth tells that Zeus transformed Io to disguise her from his jealous wife, Hera. According to another myth, Hera transformed Io to punish her and to break up her love affair with Zeus.
Hera sent a gadfly to torment Io and ordered Argus, a huge monster with 100 eyes, to guard her from Zeus. Hermes, the messenger of the gods, killed Argus, but the gadfly continued to torment Io and pursued her over the earth. She finally found peace in Egypt, where Zeus changed her back into a woman. In Egypt, Io gave birth to a son, Epaphus, the ancestor of many mythological kings and of the hero Hercules. Io was often identified with the Egyptian goddess Isis.
