Donna Noble
"Turn Left" revealed that UNIT was involved in investigating the attempted Racnoss invasion, independently of the Doctor. In the alternative universe created in that episode by the Tenth Doctor's death, one UNIT team discovered the Doctor's body, whilst another under Captain Erisa Magambo and Rose Tyler salvaged "surface technology" from the Doctor's dying TARDIS in order to send Donna Noble back in time and prevent the Doctor's death.