|“||We choose to watch Doctor Who in this decade not because it is easy, but because it is hard.||”|
— JFK's speech at the commencement of the first /who/ general.
John "Jack Harkness" Fitzgerald Kennedy, also known as JFK or "There's this friend I have", was president of the United States right up until Doctor Who started. The day before it was set to premiere, he committed suicide by self-ordered assassination rather than live in a world where Doctor Who was allowed to air.
Relationship with the ProgramEditIn Rose, it's revealed that the Ninth Doctor was the man on the grassy knoll, presumably ensuring that JFK wouldn't be able to seduce his every female companion for the foreseeable future.
One of the Virgin authors revealed he was, in fact, the assassin, apparently?
Doctor Who: Born with John F. Kennedy, died with John N. Turner.