Who is Master Chief?

Known primarily by his rank, Master Chief is a product of the SPARTAN II project – the systematic raising of children to become Earth's most formidable warriors in the 26th century. Each child is trained, educated and enhanced using the very best tactics, technology and medicine. The result is a mentally and physically superior human being, augmented with, in the case of Master Chief, energy shielded Mark VI Mjolnir Battle Armor.
Master Chief, Spartan 117 may be the last of his kind. Years of conflict with the aggressive alien culture known as The Covenant, have depleted the Spartan ranks, and beaten human forces back from their exploration of the Orion arm of the Galaxy. Master Chief is tenacious, professional and incredibly skilled in all current forms of armed combat. Standing at around seven feet tall, with incredible reflexes and prodigious physical strength, he presents an intimidating figure, even to Covenant warriors, who already know him from his exploits at Halo.