Doctor Who: Every Character Who Can Fly The TARDIS
3. Tasha Lem
Like River Song, Tasha Lem clearly has a close, personal connection with the Doctor, but in this case, that connection has yet to be explored.
Leader of a religious group called The Church in Eleven's swansong episode The Time Of The Doctor, Tasha's interactions with the Doctor - flirting, kissing, bickering like an old married couple - hint at a juicy backstory that we never got to see. Indeed, there are countless questions surrounding Tasha and her history, and the fact that she can fly the TARDIS only adds to this air of mystery.
In one scene near the end of the episode, Tasha rides the TARDIS solo, picking up Clara Oswald so that she can return to Trenzalore and say goodbye to the Doctor, who is about to regenerate. Interestingly, Tasha states that flying the TARDIS is "easy" - it's flying the Doctor that she never quite got the hang of.
There's definitely an innuendo in there somewhere.
We haven't seen Tasha since this episode ended, but despite her small amount of screen time, her TARDIS piloting skills rank her as one of the most unique characters in Doctor Who history.