Io (Ancient Greek: Ἰώ) was, in Greek mythology, a priestess of Hera in Argos, a nymph who was seduced by Zeus, who changed her into a heifer to escape detection. His wife Hera sent ever-watchful Argus Panoptes, with 100 eyes, to watch 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 (Cadmus was also named as a son of Belus' brother Agenor) and Danaus would then "return" to mainland Greece. In the 2010 film Clash of the Titans, Io was portrayed by British actress Gemma Arterton. Meaning of the name is unknown.