Master Chief Petty Officer John-117, also known as simply John-117 or Master Chief, is a Spartan-II commando of the UNSC Naval Special Warfare Command who became one of the most important UNSC heroes during the Human-Covenant war. With over thirty years of active duty, he has become one of the most decorated war veterans in the United Nations Space Command, earning every known UNSC medal except the Prisoner of War Medallion. His goal is to save humanity from hostile alien races. John-117 is the protagonist and main playable character in both the Halo trilogy and Reclaimer Saga.