Argus or Argos Panoptes (, "All-seeing Argos") is a many-eyed giant in Greek mythology. Mythology Argus Panoptes (), guardian of the heifer-nymph Io and son of Arestor and probably Mycene (in other version son of Gaia), was a primordial giant whose epithet Panoptes, "all-seeing", led to his being described with multiple, often one hundred, eyes. The epithet Panoptes was applied to the god of the Sun, Helios, and was taken up as an epithet by Zeus, Zeus Panoptes. "In a way," Walter Burkert observes, "the power and order of Argos the city are embodied in Argos the neatherd, lord of the herd and lord of the land, whose name itself is the name of the land."The epithet Panoptes, reflecting his mythic role, set by Hera as a very effective watchman of Io, was described in a fragment of a lost poem Aigimios, attributed to Hesiod: In the 5th century and later, Argus' wakeful alertness was explained for an increasingly literal culture as his having so many eyes that only a few of the eyes would sleep at a time: there were always eyes still awake. In the 2nd century AD Pausanias noted at Argos, in the temple of Zeus Larissaios, an archaic image of Zeus with a third eye in the center of his forehead, allegedly Priam's Zeus Herkeios purloined from Troy. Argus was Hera's servant. His great service to the Olympian pantheon was to slay the chthonic serpent-legged monster Echidna as she slept in her cave. Hera's defining task for Argus was to guard the white heifer Io from Zeus, who was attracted to her, keeping her chained to the sacred olive tree at the Argive Heraion. She required someone who had at least a hundred eyes spread out, always watching in all directions, someone who would stay awake despite being asleep. Argos was meant to be the perfect guardian. She charged him to "Tether this cow safely to an olive-tree at Nemea". Hera knew that the heifer was in reality Io, one of the many nymphs Zeus was coupling with to establish a new order. To free Io, Zeus had Argus slain by Hermes. The messenger of the Olympian gods, disguised as a shepherd, first put all of Argus' eyes asleep with spoken charms, then slew him by hitting him with a stone, the first stain of bloodshed among the new generation of gods. After beheading Argus, Hermes