Anton-23M was a SPARTAN supersoldier. He was a candidate of the UNSC Army's MIST project, a precursor project of the SPARTAN-III program headed by Colonel James H. Ackerson, and a FORSCOM operator during the early stages of the Human-Covenant War. One of the many survivors after the Covenant invasion of Ballast, Anton-23M was transferred to the Naval administration as part of Project MIST's closure.