Martha Jones (robot)

The Martha Jones robot was a duplicate of Martha Jones created by an enemy of the Tenth Doctor's who somehow managed to infiltrate the TARDIS via teleportation. The Doctor reprogrammed her to believe that she was the real Martha Jones, but she fled after he acted hostilely towards her. The truth of her nature was revealed to her by Donna Noble, and she was subsequently left on an alien planet by the Doctor and Donna. (COMIC: Mad Martha)