Corporal Locklear was a UNSC Marine and ODST stationed on the UNSC Pillar of Autumn in 2552 as one of Major Antonio Silva's company. His first name was never mentioned. After The Battle of Reach, Locklear fled with the rest of the ship to Installation 04, where the Autumn was shot down.
He was never mentioned during The Battle of Installation 04, but was among the handful of survivors who fled in a Pelican when the Halo was destroyed. He, First Lieutenant Elias Haverson, Staff Sergeant Avery Johnson, and Warrant Officer Polaski in the debris field until they met with SPARTAN-117 and Cortana in their Longsword fighter. The Master Chief recognized that Locklear was in a state of shock from the destruction of the Halo, describing him as "An assault rifle with its safety permanently clicked off." Locklear was hesitant to accept the Master Chief's command at first, but was eventually subdued by the Chief's greater authority. He and the Master Chief then developed a closer working relationship over the course of OPERATION: FIRST STRIKE.
Locklear helped in the capture of the Covenant flagship Ascendant Justice, and was aboard when they returned to Reach. He then accompanied the Master Chief to the surface of Reach where they rescued the Spartans who had survived the fall of Reach. At some point, he developed feelings, apparently reciprocated, for Warrant Officer Polaski. He was greatly saddened when she died in the slipspace bubble caused by the Forerunner Crystal artifact.
He helped the Eridanus Rebels repair the vessel when they traveled to Eridanus Secundus While there, Dr. Catherine Halsey gave him the artifact, as she felt she could not trust ONI. She knew that Locklear would destroy it, and told him that it needed to be done.
As the battle at Eridanus Secundus began, Locklear was ordered to collect supplies from the UNSC Gettysburg. He walked into the armory of the ship, found the Ethyl Alcohol, and eventually covered the artifact with C-7 Foaming Explosive. He detonated the explosive, which caused an explosion of radiation, killing him.
Locklear's Death
It is unclear if Locklear comitted suicide, as it would at first seem. He was obviously very upset at the death of Polaski, but he also said just before the accident that he "wasn't going to die". It is possible that he was drunk, although the book does not specify whether he drank any of the alcohol or not. But also he did dive for cover behind a robotic dolly, so it can also be speculated that the incident was purely accidental.