River Song (Ghosts)

A hologram of 'River Song was created by the Tenth Doctor as part of a programmed to get a crashed ship's computer to find a solution to it creating holograms. She helped in the hologram version of the Tenth Doctor investigation. She didn't realise that she was a hologram. Her lack of memory triggered the Tenth Doctor's holograms why he was there and what was happening on the planet. (AUDIO: Ghosts)