 The role started out as that of a seemingly good doctor, but in the end, the good doctor was revealed to be the "Sin Stalker," responsible for killing off several supporting characters on the show.Other television shows O'Brien starred in include "The Adams Chronicles" (TV mini series), "The United States Steel Hour", "The Heiress" (TV Movie), "The Cosby Show" and "Spencer For Hire" (as recurring character Tom Flaherty).He also appeared in the movie "".