Doctor Who is the world's longest continually produced science fiction serial. It aired on the British BBC network from 1963 until 1989, and was revived briefly as a television movie in 1996. In the United States, Doctor Who first began broadcasts on independent channels in 1972, and was still broadcasting on some local PBS affiliates in the late 1990s. It has, like Star Trek, engendered movies, radio dramas, lucrative novel series, non-fiction, comic books, and an extensive home video market.

Doctor Who revolves around the adventures of the mysterious time-traveling title character, simply known throughout as The Doctor. The Doctor, as first seen in the 1963 pilot episode, broadcast in the midst of the BBC's coverage of the Kennedy Assassination, is outwardly human. William Hartnell, the actor to first portray the Doctor (1963-1966), presented audiences with a cranky old man who had a gross lack of basic human kindness. Initially, the...