Chief Petty Officer Thom Shephard was an Engineering Technician for the UNSC aboard the Halcyon-class light cruiser UNSC Pillar of Autumn in 2552. He, along with Tech Officer Sam Marcus, unsealed John-117 from the Cryo-chamber before the Battle of Installation 04. He ran the Chief through several diagnostics and tests of his MJOLNIR Mark V armor. Soon after, Captain Keyes called the Chief to the bridge of the ship. Thom then told the Chief to follow him to the bridge and rushed out the door, where he was killed by a conduit explosion in the wall.