Marty McFly

Marty McFly was a character in Back to the Future that the Tenth Doctor once used to illustrate the theory of infinite temporal flux to Martha. In the film, McFly "began to fade" out of existence as changes were made to his personal family history. This, the Doctor suggested, was indicative of the general malleability of time — and of what would happen to Earth's future if he and Martha could not stop the Carrionites in 1599. (TV: The Shakespeare Code)

External link

 * at the Back to the Future wiki