Argus Panoptes

Hermes killing Argus on an Attic red-figure hydria by the Eucharides Painter, ca. 490 BC, Martin von Wagner Museum.

Argus or Argos Panoptes (Ancient Greek: Ἄργος Πανόπτης, "All-seeing Argos") is a many-eyed giant, son of Gaia, in Greek mythology. Known for his perpetual vigilance, he served the goddess Hera as a watchman. His most famous task was guarding Io, a priestess of Hera, whom Zeus had transformed into a heifer. Argus's constant watch, with some of his eyes always open, made him a formidable guardian. His eventual slaying by Hermes, on Zeus's orders, is a prominent episode in the myths surrounding him, and his eyes were then incorporated into the peacock's tail by Hera in his honor.