According to historian Ephraim Lytle, the graphic novel and movie “300” have little to do with the facts, as we know them, regarding Sparta and Persia in general and the Battle of Thermopylae in particular.
For example:
And had Leonidas undergone the agoge, he would have come of age not by slaying a wolf, but by murdering unarmed helots in a rite known as the Crypteia. These helots were the Greeks indigenous to Lakonia and Messenia, reduced to slavery by the tiny fraction of the population enjoying Spartan “freedom.” By living off estates worked by helots, the Spartans could afford to be professional soldiers, although really they had no choice: securing a brutal apartheid state is a full-time job, to which end the Ephors were required to ritually declare war on the helots.