30 Days of Doctor Who: Question 28: Favourite character who appears in one episode.
Jenny, the Doctor's daughter.

From episode 4x06, "The Doctor's Daughter", of course. I loved that episode. I loved Jenny, and thought it was great to see Nigel Terry. I loved the way Donna related to both Jenny and the Doctor, and tried to reconcile them, and to find out about the Doctor's past. I loved Jenny's personality, her talents, and her fate. I loved it that Martha was in the episode, too, and did her part towards creating the peace.
I love it that Jenny is out there somewhere in the universe, having her Time Lord adventures.
I've always hoped we'll see her again.