Who is argus and why can he never be surpised?

Argus, in Greek mythology, is a giant with many eyes, often depicted as a guardian. He was tasked with watching over Io, a mortal woman transformed into a cow, making him vigilant and ever-watchful. Because of his numerous eyes—some of which remained open while others slept—he could never be fully surprised or caught off guard. Ultimately, he was slain by Hermes, who lulled him to sleep before carrying out the task.