For almost 30 years the battle between the forces of humanity and the Convenant, an aggressive collection of alien species, has raged across the galaxy. Countless moments of bravery and danger have made heroes on both sides of the war, but above all others stand the Spartan super-soldiers and their leader: the Master Chief, John-117.

Master Chief: Abducted at the age of six, John was conscripted into the Spartan-II project, trained, and augmented to be a super-soldier. A hero and a legend, the Master Chief John-117 changed the course of human history and the universe.

Cortana: The artificial intelligence or 'AI' Cortana was originally designed to infiltrate the Convenant and capture one of their Prophet leaders. This plan changed when the planet Reach fell, and Master Chief was entrusted with her safekeeping - the two developed a deep bond soon after.