Doctor Who (season 4)
The fourth season of British science fiction television series "Doctor Who" began on 10 September 1966 with the First Doctor (William Hartnell) story "The Smugglers" and, after a change of lead actor (Patrick Troughton) part-way through the series, ended on 1 July 1967 with "The Evil of the Daleks". For the first time, the entire main cast changed over the course of a single season (the only other occasion this has happened is during Season 21). Only 10 out of 43 episodes survive in the BBC archives; 33 remain missing. No serials in this season  exist in their entirety. However, "The Tenth Planet", "The Power of the Daleks", "The Moonbase", "The Macra Terror", "The Faceless Ones" and "Evil of the Daleks" have currently had their missing episodes (twenty four in total) reconstructed with animation and subsequently have been released on home media. Casting. Main cast. William Hartnell appears as the First Doctor for the first two full serials before being succeeded in the role by Patrick Troughton as the Second Doctor for the remaining seven stories. Anneke Wills and Michael Craze continue their roles as Polly and Ben respectively. They are shortly joined by Frazer  Hines playing Jamie McCrimmon in "The Highlanders". Polly and Ben depart in the penultimate story "The Faceless Ones", and at the end of the season Deborah Watling makes her debut as Victoria Waterfield in "The Evil of the Daleks". Serials. Season 4 was produced by Innes Lloyd. Gerry Davis served as Script Editor, apart from the final four episodes of "The Evil of the Daleks". Peter Bryant joined as associate producer for "The Faceless Ones", and replaced Gerry Davis as script editor for the last four episodes of the season. "The Smugglers" was the final serial to be produced during  the third production block, but was held over to the start of Season 4. "The Tenth Planet" introduced the Cybermen and the concept of Regeneration, which wouldn't be named so until "Planet of the Spiders" in 1974. "The Power of the Daleks" was the first Dalek story to use the traditional "...of the Daleks" title form. Of the nine subsequent Dalek serials, only "Death to the Daleks" from Season 11 was not named in this way. The naming convention for Dalek stories was first used in the revived series with "Evolution of the Daleks" in Series 3. While each  of the other seasons produced in black and white have at least two serials completely intact (all serials from the transition to colour onwards have surviving copies in the BBC archive), none of the nine serials from Season 4 are complete in the BBC archive, with four ("The Smugglers", "The Power of the Daleks", "The Highlanders" and "The Macra Terror") each having all of their episodes missing; of the total of 43 episodes between "Episode 1" of "The Smugglers" and "Episode 7" of "The Evil of the Daleks", only 10 are currently in the BBC archive. The most complete serial  of the season, "The Tenth Planet", is missing only its last episode; this serial, as well as "The Power of the Daleks", "The Moonbase", "The Macra Terror", "The Faceless Ones" and "The Evil of the Daleks" have had their missing elements recreated with animated episodes using the original soundtrack. Animations for Season 5 serials "The Web of Fear" and "Fury from the Deep" have also been released. The fully animated serials are presented in both colour and black and white formats, while "The Tenth Planet" and "The Moonbase" animations are presented exclusively in black and white. Production. During this season  the title card for the series was changed for the first time, starting with "The Macra Terror". Missing episodes. Season 4 is notable for being the only season of Doctor Who from which not a single complete serial survives. The missing episodes are: