The mysterious Woman in White, who appeared in The End of Time to warn Wilf, and the disgraced figure who stood at Rassilon's side; Russell T Davies claimed it was the Doctor's mother, fans speculated that it was either Romana or Susan. But now we know that a splinter of Clara existed as a Gallifreyan (advising the 1st Doctor on which TARDIS to steal), so perhaps in some future incarnation, she was still trying to help the Doctor even then?