| Doctor Who | |
|---|---|
| Season 4 | |
 Cover art of the soundtrack release for first serial of the season | |
| Starring | |
| No. of stories | 9 |
| No. of episodes | 43 (33 missing) |
| Release | |
| Original network | BBC1 |
| Original release | 10 September 1966 – 1 July 1967 |
| Season chronology | |
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 occasions this has happened are during Season 18 and 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 Underwater Menace, The Moonbase, The Macra Terror, The Faceless Ones and The Evil of the Daleks have currently had their missing episodes (twenty five in total) reconstructed with animation and subsequently have been released on home media.