Back To The Future stars Michael J. Fox and Christopher Lloyd are set to reunite on the small screen. Lloyd, who played eccentric scientist Doc Emmett Brown in the movie franchise, is to make a guest appearance in Fox's new U.S. sitcom The Michael J. Fox Show. Sources tell The Hollywood Reporter Lloyd will play the zany high school principal at the school where Fox's TV wife, played by Betsy Brandt, teaches. Brooke Shields and Sting have also booked guest spots on the show.