Astinos was the son of Captain Artemis, (historically known as Alexandros) and a member of the three hundred Spartans whom King Leonidas led to Thermopylae to confront the Persian invaders. As indicated several times in the film, Astinos appears to be a good friend to the Spartan Stelios (who represented the historical figure Dienekes). At the end of the second day at Thermopylae, after fighting bravely, Astinos was killed. His death came at the hands of a horseback Persian warrior, who cut his head off with an axe. Upon witnessing Astinos death, Captain Artemis went into a blood drunk rage that required him to be restrained by his fellow Spartans.