Evja

 was Grand High Seer of the Unon, and Observer of the Seven Realities. She brought Captain Jack Harkness into a sub-dimensional void as "insurance". Jack got her attention, and asked her what the future without the Doctor, just the Unon in charge of time, was like. When she did this, she freed Jack and helped save the Ninth Doctor from being attacked from behind. When she learned that the Doctor could not stop the entropy engine from destroying itself and the Perpetual City, she was ready to resign to her fate. But the Doctor took her and other Unons to another world giving them a "fresh start" but asking her to promise that the universe would be left to look after itself. (COMIC: Weapons of Past Destruction)