The Watchmaker was a powerful Time Lord who was married to one of Rassilon's generals early in Gallifreyan history. As the Time Lords were about to win their war against the Vondrax, their enemies created a paradox that erased her husband from the timeline. The Watchmaker was the only one who could remember him and swore to bring him back. She changed time several times while attempting to bring him back, so much that she became less of a Time Lord and more a wraith-like creature.
The Watchmaker helped Romana II and Leela to influence the timelines and create a future for Gallifrey that avoided the disasters they had witnessed. She then appeared to Irving Braxiatel and offered to help sort out the paradox that was his timeline. (AUDIO: Enemy Lines)