Corporal Marshall Webb is a Sentinel who was a member of Specter Team. Little is known about him, besides the fact that he and the rest of Specter Team, were operating in Europe searching and recovering Gray Tech as well as anything else that might be useful for SRPA scientists. In Kirkwall, Scotland he recovered the Chimeran Marksman Rifle, which after testing by SRPA was modified into the current Human-made Marksman.