Marshall (Earthshock)

Marshall was a trooper under Lieutenant Scott who ventured into a cave system to investigate the disappearance of seven members of Professor Kyle's archaeological expedition.

After the Fifth Doctor discovered a hidden Cyber-bomb in the caves, he told Nyssa and Tegan to escort Scott, Kyle, Marshall and what remained of the troops to the TARDIS to wait. After the Doctor disarmed the bomb, Scott requested that he, Kyle and the troops accompany them to meet whoever placed the bomb in the caves.

The TARDIS landed on a freighter, and the Doctor and Adric ventured outside to have a look round. Growing impatient, Scott took, Marshall, Brooks, Tegan and another trooper outside to search for them, but returned after they became separated from Tegan.

Scott, Marshall and Brooks later left the TARDIS and ventured outside again to go to the bridge to investigate. On the steps leading up to the bridge, Scott told Marshall to stay at the steps to act as a rear-guard. He later manned the barricade outside the bridge with Scott when the Cybermen attempted to storm it but was killed during the battle. (TV: Earthshock)

Behind the scenes
Marshall was played uncredited by either Stephen Whyment or Jonathan Evans. His death was not shown or referenced on screen (although a prone body can be seen lying next to Scott at the conclusion of the battle with his face out of shot), but can be inferred from him not being present when the survivors evacuated the freighter.