Master Chief (John 117)

The greatest achievement of the UNSC to date, the SPARTAN-II warriors are the pride of the military High Command. Genetically-engineered, these soldiers are encased in state-of-the-art battle suits. These suits, or "MJOLNIR Battle Armor", are bio-engineered to directly interface with the hosts brain. This provides a direct linkbetween the armor and the soldier inside, improving reaction time and reflex potential. The plating of the suit is nearly invincible, and internally the suit can regulate its temperature and provide a useful HUD display for the soldier inside.

Combining man with machine, these SPARTAN-II soldiers were originally intended by the UNSC to be used for covert infiltration's. Their mission: To board a Covenant ship, locate the aliens homeworld, and destroy it. However, a surprise attack by the Covenant on the human military stronghold of Reach annihilated all but one of these "super soldiers". The Master Chief, as he likes to be called, is now the last surviving SPARTAN-II warrior. Onboard the Pillar of Autumn, he waits silently inside the "hushed casket", for a mission that may never be...

Cortana

First invented many years ago by a joint-effort between the government and scientists, the Advanced Ship-Board AI has certainly evolved from its original programming. Now directly interfaced with any UNSC ship, these AI's help pilot and navigate the fleets dedicated to protecting Earth. After the Cole Protocol was instigated a few years ago, it has now been deemed that destruction of a ship-board AI is unacceptable, and that they must be protected at all costs.

Cortana, one of the more advanced of these AI's, resides onboard the Pillar of Autumn. Her unique design allows her to be uploaded into any battle suit or electronic device with relative ease. She can quickly hack into alien computer systems, and is known for intercepting enemy intelligence and communications. She also assists her commander, Captain Jacob Keyes, with troop deployments and strategies.

Captain Jacob Keyes

From his young days as a boy on Earth, Jacob Keyes has always had his eyes and dreams turned to the stars. As he grew older and wiser, Keyes found a great interest in commanding. From his years as class president to his career in the military, it looked as if Jacob Keyes was born to lead. Eventually he joined the United Nations Space Command, a dream that he had known since he was a boy. It would prove to be a critical decision in the years that would follow.

Twenty-six years later, Jacob Keyes is still working for the UNSC in his military career. Now promoted to the rank of Captain, Keyes has been recognized as an excellent strategist and inspirational leader. The men under his command trust him with their lives, willing to give it at any he moment should he ask. Keyes is also known for many acts of bravery and heroism. In turn, the UNSC has granted him with a top-secret mission of the most importance. The cargo he carries aboard his ship, The Pillar of Autumn, may very well turn the tide of war against the Covenant...

The Marines (United Nations Space Command)

Rugged, diverse, and strong, these men are the fighting force that gives the UNSC its backbone. Always the first ones in and last ones out, these soldiers are trained to fight in any condition or situation that may arise on the battlefield. Although out-gunned and out-numbered by the Covenants forces, these marines will never surrender, even as their numbers dwindle. They're the best of the best- but they're only human.

Grunts

Serving as the main forces for the Covenant, these "grunts" make up the majority of these alien hordes. Standing approximately 5' tall, grunts are generally very weak and cowardly. While easily defeated individually, grunts are known to be a powerful force to reckon with when in large numbers. These numbers can sometimes range from hundreds to thousands, all with a single purpose in mind.

Normally entering the battlefield in light cases of armor, grunts require a life-support system to survive. This appears to be integrated into the suits that they wear. Also, the color of these suits (ranging from orange to red) are used to indicate rank. Grunts are regularly seen carrying plasma pistols, but some have been known to use plasma riffles and grenades.

Jackals

Using their superior senses of sight, hearing, and smell, the Jackals serve as the eyes and ears of the Covenant forces. Generally used as scouts, they have also been rumored for being used in assassinations and executions. On the battlefield, it has been known for Jackals to line themselves in rows stretching miles across, creating a near-invincible wall of shield.

Wielding a plasma pistol, Jackals are easily recognized with their usage of the mobile energy shield. With a weapon in one hand and a shield in the other, a Jackal can hold his own against even a whole squad of marines. Although the shield does regenerate after taking damage, they have been known to shatter under energy weapon fire.

Elites

Without a doubt, the sight of an elite will be enough to strike fear and terror into the most battle-hardened veteran. Standing at an amazing height of 8'6'' tall, these warriors have incredible strength. Combining this brute force with their excellent marksmanship, the Elites are a force to be reckoned with. But for even more extensive protection, the Elites are equipped with a full-body shield. Much like energy shields, it can recharge when depleted.

Along with this shear power and strength, Elites also serve as the brilliant tacticians and generals commanding the Covenant armies. The roles that each Elite plays, much like the Grunt, is determined by color. Generally blue Elites are front-line soldiers, with red ones acting more as scouts. There are also invisible gray Elites that serve as assassins or covert infiltration's, with the golden Elites serving as heavy-assault troopers, and the black elites are much like special operations. Each Elite is always armed with a plasma pistol or needler, and plasma grenades.

Hunters

Little is known about these hulking beasts, mainly due to the fact that so few have survived the encounter. Towering over the battlefield at 12' tall, a Hunter is capable of tearing through any enemy defense. Nearly invincible in their huge casings of armor, the Hunters also carry around a massive shield. Made of a nearly-impervious metal alloy, the shield is occasionally used as a melee weapon. Furthermore, Hunters have a fuel rod gun directly integrated into their armor, making them the perfect offensive and defensive soldier.

Infection/Maggot

The infection form or maggots are quite small, and vulnerable to physical attack. To compensate, it is very numerous, and rather fast. It can move across the ground, or along walls, and for short distances is capable of large jumps. If it comes in contact with an energy shield, it explodes, or "pops" and little or no damage has been done... but when there is no shield it will latch on to the host and embed itself in the host's chest cavity, taking over all motor functions.

Adult - Covenant

The Covenant Warrior Form is a formidable enemy; it is capable of a deadly physical attack using its tentacles (once the arms of the Covenant host), as well as having the ability to wield both human and Covenant weapons. It is very fast, very strong, and can jump great distances. Due to the Flood Controller's indifference to its host's discomfort, it is nearly immune to some weapons (notably the sniper rifle), but reliance on the host life support systems render it vulnerable to shotgun blasts. It does not have the capability of using Covenant Energy Shields, though it does, on occasion, use Active Cloaking Devices.

Adult - Humans

The Human Warrior Form is significantly smaller than the Covenant version (due to the comparative differences of the host bodies), and is both slower and weaker than its Covenant counterpart (though it has the same jumping ability). It shows a preference for human weapons, and can be deadly with a shotgun in close quarters. As with other Warrior Forms, it is capable of sustaining massive physical damage before being unusable to the Flood Controller; in fact, as long as the chest cavity and legs remain intact, it will continue to try and fight.

Carrier/Exploders

Within the Carrier Form the spores (Infection Form or maggots) are created/nurtured. The Carrier form come in two variants - they're either Flood-infected Grunts (the Flood don't consider Grunts an effective combat form), or they're Warrior forms (either human or Covenant) so badly damaged they're no longer fit for battle. The reason their legs are so short is because they're missing the bottom half, in most cases - their 'feet' were once knees. In either case, their primary purpose is the same: they serve as a portable incubator for future spores. The Carrier Form is quite slow, but responds to damage by simply releasing its offspring in an explosive rush; it is capable of killing or disabling nearby beings (friend or enemy, it's indiscriminate) when it detonates. It will detonate itself if it gets close enough to an enemy target.