Thought to be the last surviving SPARTAN soldier, Master Chief possesses a unique trait that has made him both a hero and symbol of hope in the eyes of humanity, and a "demon" in the minds of his enemies. That trait? A rare combination of skill and luck that has seen him through many battles, including the destruction of two HALO installations.

Be mindful of your surroundings, for one never knows when one is being hunted. Invisible to all but the keenest of eyes, Brute Stalkers use light-bending technology known as active camouflage to approach their prey undetected, before unleashing destruction upon their unsuspecting enemies.

Orbital Drop Shock Troopers (ODST) are an elite branch of the United Nations Space Command (UNSC) special forces. Comprised of an all-volunteer fighting force of some of the bravest men the UNSC has to offer, the ODST have served valiantly in many campaigns against the Covenant, including engagements on three separate HALO installations.

Another weapon in the mighty Covenant arsenal, Drones (or "buggers") are insect-like warriors that attack in swarms -- the buzzing static of their wings offering the only warning of their approach. Drones are dangerous opponents in any battle, as their ability to fly offers them many angles from which to attack, and their erratic flight patterns make for difficult targets.

Though considered a high commander of the Elites, the Arbiter lost his honor among the Prophets when he failed to protect the first HALO. Disillusioned by the reason behind the Covenant's war against humanity, the Arbiter leads the Elites when they align with the UNSC.