Leinidus, more commonly known as Leonidas I, was a king of the Greek city-state of Sparta who reigned from around 490 to 480 BC. He is best known for his leadership during the Battle of Thermopylae in 480 BC, where he and a small force of Spartans and other Greek allies famously held off a much larger Persian army led by King Xerxes. Leonidas is celebrated for his bravery and sacrifice, embodying the Spartan ideals of courage and honor in battle. His legacy has inspired countless works of literature and film, particularly in the context of heroism and resistance against overwhelming odds.