Chief Petty Officer Callie Hall, designated as SPARTAN-141, was a SPARTAN-II commando under the UNSC Navy's Special Weapons division of Naval Special Warfare. She is known by her codename as "Calypso", given to her by the Office of Naval Intelligence during her work with Delta-4 Division. She was known to have a strong interest in Greek mythology, including it's ancient Hellenistic philosophy.