Melissa McKay

First Lieutenant Melissa McKay was a Company Grade officer in the UNSC Marine Corps. She was the Executive Officer of the 22nd Shock Battalion, under command of Major Antonio Silva.

She was stationed on the then, newly refit during the Battle of Installation 04.

Appearance
Lieutenant McKay is described as having her hair worn short on the sides and flat on the top (so the tattoos on her scalp could be seen) accompanied by a slightly flattened nose, full lips, and green eyes.

Commands
In addition to being the Battalion's XO, she personally commanded a company of some 130 Marine Shock Troops aboard the Autumn. Her platoon commanders were Second Lieutenant Dalu and Second Lieutenant Oros. However, Dalu was later reassigned as the Company Supply Officer and his billet was taken by Master Sergeant Lister.

Retreating from Reach
When the vessel fled the Battle of Reach, she was wounded in action by Covenant Naval Infantry boarding parties. Nonetheless, she made the jump from the Pillar of Autumn to the surface of Installation 04 aboard a Human Entry Vehicle.

Landing on Installation 04
She was third in command of the survivors of the Autumn, under Captain Jacob Keyes and Major Antonio Silva, and helped secure the Pillar of Autumn's crash site.

After leading the attack to capture the mesa that would become Alpha Base, she met Master Chief Petty Officer John-117 for the first time. Though Major Silva was very antagonistic toward the Chief, McKay was one of few Shock Troopers to actually look up to the Chief. She figured that it was a matter that Major Silva, and men in general, would not understand.

By order of Silva, she led a convoy of Warthogs and Scorpions from the crash site of the Autumn. On the way back to the base, they encountered resistance from Covenant forces under field master Noga 'Putumee. Nevertheless, she managed to ferry a large number of supplies from the ship to the base.

Attack on Alpha Base
The next day she, along with other ODST's, saw and took prisoner the "wounded" Minor Yayap; little did she know that Yayap would trigger an attack later on.

Later she was at Alpha Base when Commander Zuka 'Zamamee and other Elites attempted to infiltrate the base to find the veteran SPARTAN. She then organized several rifle squads to help fend the attack off from Alpha Base. After the attack, she took the remains of Charlie 217, the D77-TC Pelican Dropship used by the Sangheili to infiltrate, and set them up as though the ship had crashed so that the Covenant would come and the Humans could ambush them.

The Covenant came, but so did the Flood. Lieutenant McKay was horrified at the first sight of the Flood. Nevertheless, she managed to capture one Combat Form alive, the form of the former PFC Wallace A. Jenkins. She, along with Silva, interrogated him and compiled the first tactical information on the Flood.

Later, using Jenkins' information, she helped to prevent an attack on the base by the Flood long enough to evacuate it.

Raid on the Truth and Reconciliation
She then assisted in the attack on the Covenant-held Truth and Reconciliation, having guards drag Private Jenkins along for the ride.

After the vessel's capture, McKay realized that Silva was planning on taking the vessel to Earth so that he could become the hero of the people. She realized that this was not only in violation of the Cole Protocol, but that if a single Flood Form made it to Earth, all of humanity could fall to the Flood. Most of the vessel had not yet been sterilized from the Flood when Silva ordered it to take off.

Death
McKay disobeyed Major Silva's direct orders by priming a grenade and setting it off, killing her and numerous others instantly, including an infected Private First Class Wallace A. Jenkins, severing the cruiser's fiber-optics connection to the reactors bridge to keep the Flood from escaping the Halo. Her actions killed not only her, but other Marine and Naval personnel their lives, thought stopped the Flood from killing millions, if not billions, of sentient lifeforms throughout the Milky Way galaxy.