8 October 1966 The Cybermen make their first appearance, giving Doctor Who its second enduring monster.
29 October 1966 In the closing minutes of The Tenth Planet, the Doctor regenerates for the first time (though that term won’t be used until the Third Doctor changes into the Fourth), and William Hartnell makes his final regular appearance in the series. Patrick Troughton briefly makes his Doctor Who debut.
5 November 1966 Patrick Troughton’s first full episode as the Doctor also sees the return of the Daleks.
17 December 1966 The first appearance of Frazer Hines as Jamie Macrimmon. He will clock up 113 regular episodes of Doctor Who, the most of any companion.
4 March 1967 The series sees its first use of an optical special effect, as the Cybermen blast a hole in the wall of a moonbase with a space cannon.
11 March 1967 The debut of a revamped title sequence featuring the face of Patrick Troughton. This creates a tradition of using the Doctor’s face in the titles that lasts until 1989 – a custom absent from the Eighth, Ninth, Tenth and early Eleventh Doctors’ eras but reintroduced on 25 December 2012.
1 July 1967 The Daleks make what is intended to be their final appearance in Doctor Who. This ‘final end’ is brought about by writer Terry Nation’s desire to launch his creations in their own series. The BBC has turned down the chance to make such a spin-off, and Nation has opened talks with American broadcasters. The monsters that helped cement Doctor Who’s popularity will not return to the series in a new story for nearly five years.
30 September 1967 The first appearances of the Yeti and the Great Intelligence.
11 November 1967 The first appearance of the Ice Warriors.
17 February 1968 The first appearance of Nicholas Courtney as Colonel Lethbridge-Stewart. The character’s feet have appeared in close-up a week earlier, provided by extra Maurice Brooks.
16 March 1968 The first appearance of the sonic screwdriver.
9 November 1968 The first full appearance of UNIT, the United Nations Intelligence Taskforce, under the command of Alistair Lethbridge-Stewart, now a Brigadier, played once again – and many times in the future – by Nicholas Courtney.
7 January 1969 The announcement to the press that Patrick Troughton is to leave Doctor Who.
7 June 1969 The first use of ‘Time Lord’ to describe the Doctor’s people, uttered by an unnamed scientist played by Vernon Dobtcheff in The War Games.
17 June 1969 Jon Pertwee is announced as the third actor to take on the TV role of the Doctor in a press call held at BBC Broadcasting House. The actor is accompanied by a Yeti.
21 June 1969 Patrick Troughton’s final regular appearance as the Doctor. This episode features the first trip to the Doctor’s as yet unnamed home planet.
3 January 1970 A date marking many firsts in the history of Doctor Who. Jon Pertwee makes his debut, and a format change sees the Doctor exiled to Earth by the Time Lords. The Third Doctor becomes scientific adviser to UNIT with Nicholas Courtney’s Brigadier Alistair Lethbridge-Stewart joining the series as a regular. The Nestene Consciousness and its plastic servants, the Autons, make their first attempt to invade Earth. Technology is changing in the wider world of television, and Doctor Who is broadcast in colour for the first time with a story recorded entirely on film, something that won’t happen again until 1996. The series sports a new colour title sequence featuring Pertwee’s face, and the number of episodes for the series has been reduced. Instead of running for about ten months of the year, as it has since 1963, Doctor Who is now on air for six months.
31 January 1970Doctor Who and the Silurians marks the only time the series name is used within an individual on-screen story title. The Doctor’s yellow vintage car Bessie makes her debut. The appearance of a dinosaur marks the first use in the series of a technique known as colour separation overlay, or chromakey. A primary-coloured backdrop is used to ‘key in’ an image from another camera in a similar way to today’s green-screen technique.
21 March 1970 The theme tune ‘sting’ to emphasise the cliffhanger ending to each episode is used for the first time at the suggestion of director Michael Ferguson.
2 January 1971 Roger Delgado arrives as the Doctor’s Time Lord arch nemesis the Master.
1 January 1972Day of the Daleks Episode 1 sees Skaro’s finest make their first appearance since May 1967.
29 January 1972 The Ice Warriors return as the Doctor faces The Curse of Peladon, although this time they’re goodies!
26 February 1972 The first appearance of the Sea Devils.
30 December 1972 A milestone to mark the tenth anniversary of the series, as William Hartnell and Patrick Troughton return to Doctor Who, battling the Time Lord Omega with current Doctor Jon Pertwee in The Three Doctors.
31 March 1973 The final appearance by Roger Delgado as the Master in the story Frontier in Space.
7 April 1973 Dalek creator Terry Nation makes his first script contribution to Doctor Who for seven years with Planet of the Daleks Episode 1.
2 May 1973 Target Books publish reprints of the novelisations Doctor Who and the Daleks, Doctor Who and the Crusaders – both by David Whitaker – and Doctor Who and the Zarbi by Bill Strutton.
18 June 1973 Roger Delgado is tragically killed in a car accident while filming Bell of Tibet in Turkey.
26 June 1973 Elisabeth Sladen is announced to the press as new companion Sarah Jane Smith, with Jon Pertwee joining her at a photo call at BBC Television Centre.
15 December 1973 The first episode of Doctor Who’s 11th season not only sees Sarah Jane Smith join the TARDIS, but also features the debut of the potato-headed Sontarans. The series now sports a brand new title sequence, once again designed by Bernard Lodge, who has created each title sequence since Doctor Who’s first episode. Lodge also designs a diamond-shaped logo to accompany the new series.
22 December 1973 The first on-screen reference to Gallifrey as the home planet of the Doctor and the Time Lords. This is not the first time the name has cropped up: it has been let slip in issue 124 of TV Action comic in July 1973, as the editors responded to a reader’s letter asking which planet the Master came from.
5 February 1974 BBC Head of Serials Bill Slater receives a letter from an out-of-work actor called Tom Baker, asking for work.
8 February 1974 The press announcement that Jon Pertwee will leave Doctor Who at the end of the current series.
15 February 1974 Tom Baker is unveiled to the press as Jon Pertwee’s successor in the role of the Doctor. He is joined by Elisabeth Sladen and a Cyberman at a photo call at BBC Television Centre.
8 June 1974 The final regular appearance by Jon Pertwee as the Doctor after five years. The term ‘regeneration’ is used for the first time.
28 December 1974 Tom Baker makes his full debut as the Doctor at 5.35pm, watched by 10.8 million viewers. Bernard Lodge’s fifth title sequence is unveiled, which now features Tom Baker’s face and the TARDIS for the first time.