This topic might have a better name.
Blake (The Christmas Invasion). Not named at all in dialogue other than "the Major", but he's credited Major Blake in the credits of Invasion.
Talk about it here.
Major Richard Blake was the UNIT officer in charge of the Tower of London branch of UNIT. He briefed Harriet Jones and Daniel Llewellyn on the protocols of dealing with extraterrestrial beings and was with them when all three were teleported aboard the Sycorax ship. After the death of Llewellyn, Blake tried to protect Harriet Jones and Alex Klein by protesting Llewellyn's cold blooded death, but died when the Sycorax leader struck him with his energy whip. (TV: The Christmas Invasion)