Master Chief Petty Officer of the Navy John-117, popularly referred to simply as the "Master Chief," is a soldier in the United Nations Space Command and a member of the Spartan-II program. He is the main protagonist of the Halo trilogy and the last active Spartan in the series. Always seen donning MJOLNIR full-body powered armor, his face has never been revealed. John-117 very intelligent and skilled in combat, and he is often thought of as the best Spartan. He has seen action in almost every major conflict between the UNSC and Covenant Empire, from Harvest to the Battle of Installation 00. He was responsible for the destruction of Installation 04 (Alpha Halo), which eventually led to the split and defeat of the Covenant. Look up Master Chief or John-117 on Halo Nation for a more detailed description.