Leonidas is a Greek name that means "son of the lion" or "lion-like", from leon, lion. King Leonidas of Sparta led the 300 at Thermopylae in 480 BC, and the 2006 film 300 brought that story, and the name, to a new generation of American parents. Leonidas entered the US top 1000 in 2008, peaked at number 421 in 2022 and ranks number 510 in 2025.