Grey (The Ambassadors of Death)

Grey was a soldier who acted as General George Carrington's aide and radioman. He was a "powerful-looking thick-set young man" with light, close-cropped hair and a heavy moustache. (PROSE: The Ambassadors of Death)

On General Carrington's orders, Grey sent a message to the aliens to bring them to Earth, after which he and the general captured Mars Probe 7. However, the Third Doctor held them up using Bessie and stole their vehicle, taking the craft to Space Control. (TV: The Ambassadors of Death)

Behind the scenes
Grey is never referred to by name onscreen. However, he is identified as Grey by the credits and by the novelisation.