MJOLNIR battle armor is a fictional battle armor in the Halo series of video games and novels used by the Spartan II super soldiers, most notably by the series's protagonist Master Chief.

Soldiers have used performance enhancing equipment for hundreds of years, and the MJOLNIR battle armor represents the current pinnacle of military technology. The armor was envisioned by Dr. Catherine Halsey, who realized that no normal human could wear the armor without injuring himself. The Spartan II Project was created to create super soldiers capable of using the armor to devastating advantage.

The lethality of this system was demonstrated by the Master Chief in Halo: Combat Evolved, when he and his AI construct Cortana fought their way across a planet-like ring world called Halo.

The name of the suit is also the name for the hammer of Thor.

Armor versions

Several versions of MJOLNIR armor exist, and each generation of armor offers improvements over earlier models. Models are designated by the notation "Mark n". For example, a Mark V model is newer than a Mark IV.

MJOLNIR Mark VI

The Mark VI represents the current pinnacle of battle armor that began with the Mark I prototype. The shielding on Mark VIs recharges much faster than previous models.

Integrated into this combat suit is a dynamic, sophisticated shielding system, copied from captured Covenant technology, that repels mass objects and energy bursts, but then regenerates once the Spartan II moves away from the barrage. The accompanying computer system continuously monitors weapons, shields, biological function, motion (through a intelligent motion-sensing radar), and contains a special partition for an AI, which is intended to assist the Spartan II real-time by monitoring communication channels, computer relays, and friendly combat updates. In addition to interfacing with UNSC-standard data links, the MJOLNIR armor is also compatible with Covenant datalinks, allowing the wearer to access Covenant weapons and battle nets.

The MJOLNIR armored suit is powered by two integrated power supplies, although whether they are batteries or reactor mass is unclear. The cost of the power packs, based off the discussion with the Gunnery Sergeant at the beginning of Halo 2, is astronomical.

Unfortunately, the Mark VI's physical armor is significantly weaker than that of the Mark V once the shield has been disrupted. Without energy shielding, the Mark VI can only protect against a couple of shots before the wearer is killed.

MJOLNIR Mark V

The Master Chief wears the MJOLNIR MK V armor through the events of Halo: Combat Evolved. It features shields stronger than those on the Mark VI, but the shields do not recharge as quickly, which can leave the wearer vulnerable for extended periods of time. The armor also contains a myriad of features, including advanced communications gear and a slot for an advanced AI construct.

The physical armor beneath the Mark V's shielding is specifically designed for combat with the Covenant. It resists the Covenant's plasma-based weaponry extremely well; even with the suit's energy shielding disabled, a SPARTAN soldier can survive around three times as much damage from plasma weapons that an ordinary human (or unshielded Elite) could. Unfortunately, the Mark V provides no more protection against human ballistic weapons than that given by the armor vests worn by regular marines.

The MJOLNIR Mark IV cyborg

The numbering of Halo's MJOLNIR battle armor series is one of many references to Bungie's earlier Marathon series. During the course of the Marathon games, various text terminals make mention of ten Mjolnir Mark IV cyborgs, which represent "all of the destructive knowledge of mankind."

The identity of the player's character is never solidly stated in the games. The manual states that he is a security officer aboard the UESC Marathon. However, in the Marathon 2 preview, the AI Durandal reveals the following:

"Were you ever curious about the tenth cyborg which was supposed to be on the Marathon? Why could Leela find only nine? Was it ever activated? Was it destroyed during the defense of the colony? You are right to be curious."

This and other clues have lead many fans of the series to the conclusion that the player is the tenth Mjolnir Mark IV cyborg.