Harvey (Invaders Invisible)

Captain Harvey was a UNIT officer under Brigadier Lethbridge-Stewart. He and Liz Shaw became possessed by a sentient virus which had arrived near his base. They planned to inoculate the rest of the UNIT soldiers with the virus as part of its plan to conquer Earth, but they were freed when the Third Doctor used an x-ray machine on them. (DWAN: Invaders Invisible)