The longest-running science fiction show in history is a fine place to start this list. Doctor Who has been a BBC mainstay since 1963, which is kind of brain-melting when you think about it. The titular Doctor is what's known as a Time Lord from the planet Gallifrey, on the run from his fellow men in a stolen TARDIS. He jumps through time and space solving problems with his wits, accompanied by a revolving cast of companions. One of the most interesting aspects of the series is the many actors who have played the Doctor - since his species can regenerate from injuries, eleven different dudes have been cast in the role over the nearly half-century the show has been on.
