Before becoming a film scriptwriter, Terry Nation was a prolific writer of UK television scripts in both the action and science fiction genres. His scripts are noted for their depth, i.e. they usually have many sub-plots as well as the main plot. As a writer on the BBCs Doctor Who (1963) series, he created the Daleks, the mechanical monsters who plan universal domination. On Earth they would constantly be planning to exterminate all humans. Nation also created Survivors (1975) and Blakes 7 (1978) for the BBC.