'Star Trek: The Original Series' (TOS) is the NBC science-fiction television series created by Gene Roddenberry, which premiered on 8 September 1966 and ran for three seasons (79 episodes) through 1969. The series follows Captain James T. Kirk (William Shatner), First Officer Spock (Leonard Nimoy), and Chief Medical Officer Leonard McCoy (DeForest Kelley) aboard the Federation starship USS Enterprise on its five-year mission to explore strange new worlds. Initially a modest Nielsen performer, TOS found its audience in syndication and became the foundation of the long-running Star Trek franchise, which has grown to encompass thirteen theatrical films beginning with 'Star Trek: The Motion Picture' (1979) and eleven television spin-offs including 'Star Trek: The Next Generation' (1987), 'Deep Space Nine' (1993), and 'Star Trek: Discovery' (2017).