Leonidas I was the king of Sparta who was born around 540 BC. and is known as one of the foremost heroes of Greek antiquity. Leonidas is especially known for his role in the Battle of Thermopylae, in which he and his 300 men fought against a much larger Persian army. Although the battle ended in a Spartan defeat, the heroic resistance of Leonidas and his men inspired other Greeks to unite and fight the invading Persians.