In the BBC Eighth Doctor Adventure Novels, Faction Paradox was a time-travelling cult who created temporal paradoxes. (In their first appearance they make an old man kill himself as a young boy.) They were 'ranked' with family-relationship-sounding names, so that "Cousins" were at the first level, a "Brother" or "Sister" was higher etc. The Head of Faction Paradox was a man known as 'The Grandfather'. He was an old man with long white hair. It was never explicitly stated in the novels, but it was strongly implied that he was obviously the Doctor.
(In the real world, the "Grandfather Paradox" is a question regarding time travel. If a man goes back in time, and kills his own grandfather as a youngster, then he would never be born. But if he is never born, then he couldn't go back and kill his grandfether, so he would be born, and thus be able to go back in time to kill his grandfather. But if his grandfather dies before having children...)