Io in Wikipedia

In Greek mythology, Io (pronounced /ˈaɪ.oʊ/ or /ˈiː.oʊ/, in Ancient Greek Ἰώ /iːɔ́ː/) was a priestess of Hera in Argos,[1] a nymph who was seduced by Zeus, who changed her into a heifer to escape detection. Her mistress Hera set ever-watchful Argus Panoptes to guard her, but Hermes was sent to distract the guardian and slay him. Heifer Io was loosed to roam the world, stung by a maddening gadfly sent by Hera, and wandered to Egypt, thus placing her descendant Belus in Egypt; his sons Cadmus and Danaus would thus "return" to mainland Greece...

Link: https://en.wikipedia.org/wiki/Io_(mythology)