Margaret (Companion Piece)

Margaret was a companion of the Doctor's. She was captured by the Nine and placed in a prison along with various other companions. She could be heard bemoaning the fact that she was not young any more and begged to be let out. Like the other companions, Margaret was presumably sent home by River Song and had her memory of the prison erased. (AUDIO: Companion Piece)

Behind the Scenes
Margaret has not appeared in any other stories and it is unknown which Doctor she travelled with (although the fact that she was placed in between Leela and Romana strongly suggests it was the Fourth Doctor).