O'Brien (Reach)

Private O'Brien was one of the UNSC Marines aboard Reach Station Gamma, Dock 9, above Reach. He, along with Sergeant Johnson, PFC Jenkins, and Private Bisenti, where fighting a group of Jackals when Spartan-117 and Spartan-058 boarded the station to destroy the logs of the ONI Prowler Circumference. He was picked up with Johnson and the Chief when they took a Pelican and flew back to the Pillar of Autumn. He was killed either when the Covenant boarded the Pillar of Autumn or during the events on Installation 04.