Parker

Sergeant Parker was a non-commissioned officer in the UNSC Marine Corps and an Orbital Drop Shock Trooper. Sergeant Parker was stationed aboard the as part of the ODST detachment under First Lieutenant Melissa McKay in September 2552 during the Battle of Installation 04.

Battle of Installation 04
Like most of his comrades, Sergeant Parker abandoned the Autumn when it was attacked by the Covenant over Installation 04 using an SOEIV to drop down to the surface of the ring. He then assisted in the attack on the mesa that would be Alpha Base.

Later, he led the ODST attachment that accompanied SPARTAN John-117 on the mission to rescue Captain Jacob Keyes, who was held prisoner aboard the Truth and Reconciliation. After being deployed beneath the ship via Pelican Echo 419, Parker and his ODSTs assisted the Master Chief; John felt that the ODSTs slowed him down because they did not have the reflexes and combat skill Spartans had.

Parker was wounded by the spines of an Mgalekgolo in the vessel's cargo bay. Nevertheless, he shrugged off his wound and continued to lead the attack, liberating Captain Keyes from the brig of the vessel.

He was an efficient, personable leader. He was also very duty-minded, as he continued to fight even after sustaining a serious wound. He was noted to have teased the Master Chief, whom he treated with more respect than most ODSTs.

Discrepancy
There is some discrepancy regarding Parker's death.

In Halo: Combat Evolved, Parker was killed, along with his squad, in the Covenant control center by two Stealth Sangheili while waiting for the Master Chief to retrieve Captain Keyes from the brig. However, according the novelization, Parker was still alive and the John regrouped with him after successfully rescuing Captain Keyes. Regardless, he died during the Battle of Installation 04, along with the rest of the ODST contingent of the Pillar of Autumn (save for Corporal Locklear). Also, in the novel, Parker is stated to be male, but after he is wounded by a Hunter in the cargo bay, he is stated to be female. This is most likely a typo. See List of Inconsistencies in Halo

Quotes

 * "Covenant forces sighted! Let's hit 'em Charlie Team." - When Covenant troops are dropped from the Truth and Reconciliation.
 * "We'd be sitting ducks in that narrow space. We'll hold this position until you can find your way around and open the door from the other side, Chief." - By locked blast doors, level .