Leonidas I (/liˈɒnɪdəs, -dæs/; Doric Λεωνίδας Α´, Leōnídas A'; Ionic and Attic Greek: Λεωνίδης Α´, Leōnídēs A' [leɔːnídɛːs]; "son of the lion"; died 11 August 480 BC) was a warrior king of the Greek city-state of Sparta , and the 17th of the Agiad line; a dynasty which claimed descent from the mythological demigod Heracles and Cadmus . He was the husband of Gorgo, the daughter of Cleomenes I of Sparta. Leonidas had a notable participation in the Second Persian War, where he led the allied Greek forces to a last stand at the Battle of Thermopylae (480 BC) while attempting to defend the pass from the invading Persian army; he entered myth as the so-called leader of the 300 Spartans.
Leonidas is one of the individuals the Guardian selected for his Gene Clone program and one of the Resurrected Clones. The original Leonidas, officially killed in battle was saved by the Vrill , to become part of the secret group : Gea's Guard
(The movie 300 is loosely based on this Spartan King)