Leonidas was an ancient Greek Spartan king, known for his courage and prowess. He was the one who led 300 Spartans in the battle of Thermopylae during the Persian war. Although the Spartans were known for their harsh training and warlike manner, Leonidas stood out for his wisdom and moral leadership. The sacrifice of him and his Spartans at Thermopylae became a symbol of heroism and bravery in ancient Greek history.