Corporal Locklear
From Halopedia, the Halo wiki
Corporal Locklear was one of the few survivors of Halo. He helped the other survivors, including SPARTAN-117, capture the Covenant Flagship Ascendant Justice. He was killed when he attempted to destroy the Forerunner artifact that was found on Reach, which was creating a gravity field that kept the Gettysburg from escaping the planet.
