Carl Harris

Private Harris was a UNIT soldier in the 21th century. He was first seen ushering in a UNIT Taskforce during the Raid of the ATMOS complex. During Operation Blue Sky he discovered a cloning vat in the basement of ATMOS alongside Steve Gray. It was there that he was commended for his leadership skills by non other than a Sontaran, General Staal. Staal gave him the promotion he desired as he and Gray got hypnotised by the Sontaran to work for them. He and Private Gray captured Martha Jones in order to have her cloned and later teleported the Doctor's TARDIS onboard the Sontaran Ship. Soon after, they were killed by a Sontaran Soldier during the battle with UNIT (DW: The Sontaran Stratagem | DW: The Poison Sky)

In an alternate universe he was the UNIT officer on scene when the Doctor's body was recovered from the Thames. (DW: Turn Left)