In Greek mythology, Io was a young woman who was loved by Zeus, king of the gods. His attentions toward her aroused the jealousy of his wife, Hera *, and both deities used their powers in various ways to try to gain control over Io.
The daughter of the river god Inachus, Io was a priestess at one of Hera's temples. Zeus fell in love with her and seduced her. When Hera learned about Zeus's behavior, she turned the girl into a white cow. In some versions of the myth, it was Zeus who transformed Io into the cow, to conceal her from Hera.
After tying Io the cow to an olive tree, Hera sent Argus, a giant with 100 eyes, to watch over her. Zeus responded by sending the messenger god Hermes to rescue Io. Hermes put Argus to sleep by singing and telling stories, and then he killed the giant.
Angry that Io was released, Hera sent a gadfly—a type of insect that bites animals—to torment her. Io wandered distractedly until she reached Egypt. There, after Zeus turned her back into a woman, Io gave birth to a son named Epaphus. Many of Io's descendants returned to Greece. Among them were Cadmus, Perseus, and Hercules.
deity god or goddess
See also Argus; Cadmus; Hera; Hercules; Hermes; Perseus; Zeus.
The Bosporus (‘cow's passage’) and the Ionian Sea are reputed to have been crossed by Io, and derive their names from her story.