Steve Gray

Private Steve Gray was a UNIT soldier.

During Operation Blue Sky he was hypnotised by General Staal alongside his comrade, Private Harris. Staal had declared him an unfit soldier. He was later used to teleport the TARDIS to the Sontarans' ship, and he was killed by a Sontaran soldier alongside Harris after the pair had completed their objectives. (TV: The Sontaran Stratagem/The Poison Sky)

Alternate timeline
Along with Private Harris and Colonel Mace, he appeared to recover the body of the Tenth Doctor after he died defeating the Empress of the Racnoss in an alternate world. (TV: Turn Left)