Private First Class U. McKalla
Private First Class U. McKalla was a member Squad Bravo of the GFMC Task Force Herakles. McKalla was serving aboard the G.F.S. Tyr as a trooper when the team was forced to make an emergency landing on the planet Aether and was likely killed by the Ing-possessed Splinters that regularly attacked their Ops base.
None of the Federation Marine corpses found on Aether is explicitly said to be McKalla's. It was likely encountered as a symbiotically-reanimated Dark Trooper or hung by Worker Splinters in the Hive Tunnel.