Angus Goodman

Angus ("Gus") Goodman, travelled with the Fifth Doctor.

Biography
Gus was an American fighter pilot from a timeline in which World War II was still being fought in 1963. The Doctor had accidentally taken the TARDIS not to a holiday spot on another world as he'd intended, but to somewhere in the Pacific of that parallel Earth. Gus had crashed on the island after a dogfight with a Japanese plane. Discovering the Doctor, he put a pistol to his head, but accepted the Doctor's offer to take him off the island. (DWM: 4-Dimensional Vistas)

As was usual for the Doctor, though, he did not take Gus home by the direct route. Back in the Doctor's own universe, they first encountered the Doctor's old enemy, the renegade Time Lord known as the Monk, who had allied himself with Ice Warriors to create a gigantic sonic cannon. (DWM: 4-Dimensional Vistas)

After thwarting their plans, the two travelled to the planet Celeste, where they were captured by the malevolent frog-like businessman, Josiah W. Dogbolter. The Doctor had offended Dogbolter by refusing to sell the TARDIS to him, so Dogbolter sent a hitman, the Moderator, after him. Just as the Doctor had dropped Gus off at someplace like home, the Moderator ambushed them and shot Gus. In the ensuing hail of gunfire, Gus shot and incapacitated the Moderator. Gus died from his wounds. The Doctor left Gus where he had fallen, but would eventually encounter Dogbolter again. (DWM: The Moderator)