Grandfather Paradox, usually referred to as the Grandfather, is a fictional character in the British science fiction franchise Doctor Who and its spin-off franchise Faction Paradox. In the BBC's Eighth Doctor Adventures novels, the Grandfather is a corrupt future version of the Eighth Doctor, while in Lawrence Miles's Faction Paradox series he is a seemingly incorporeal Time Lord of unknown identity. Both narratives portray him as the founder of Faction Paradox, a time-travelling voodoo cult.