1980

Events

Victoria Waterfield visits Det-sen Monastery in Tibet, believing she is following a summons from her father. (MA: Downtime).
Sarah Jane Smith claimed to Lawrence Scarman that she have come from the year 1980, though this is disputed. (DW: Pyramids of Mars; see UNIT dating controversy).

8 - Knowing of the impending assassination of former Beatle John Lennon, The Doctor, Ace and Bernice Summerfield have traveled to New York City. Mark David Chapman, influenced by the Blue, shoots and kills him anyway. (NA: The Left-Handed Hummingbird)
25 - Professor Edward Travers, CBE, dies. (MA: Downtime)

The Doctor brings Sarah Jane Smith and Laurence Scarman from 1911 and shows them what 1980 would look like if Sutekh had succeeded in freeing himself, a lifeless Earth orbiting a dead sun. This example of alternate time convinces Sarah that they must return to 1911 and stop Sutekh. (DW: Pyramids of Mars)

5 - DW:The Horns of Nimon Episode 3 first broadcast.
12 - DW:The Horns of Nimon Episode 4 first broadcast, bringing an end to the season six weeks earlier than planned due to the cancellation of Shada. Final episode to feature the original 1960s arrangement by Delia Derbyshire of the Doctor Who theme music, specifically the arrangement introduced in the 1967 serial The Macra Terror. Also final use of the diamond-shaped series logo and Bernard Lodge "tunnel" opening sequence.
24
- Publication of Doctor Who and the Underworld.
- American edition of Doctor Who and the Android Invasion published by Pinnacle Books.

20 - Publication of Doctor Who and the Stones of Blood, by Target Books.
American edition of Doctor Who and the Seeds of Doom published by Pinnacle Books. This was the last re-print of a Doctor Who novelisation by Pinnacle, and as of 2009 stands as the last American edition of a Doctor Who novel to date.

26 - Publication of Doctor Who and the Armageddon Factor. Due to the inability of Target Books to come to an agreement with Douglas Adams, this would ultimately be the last of the Key to Time- arc serials to be novelised. The remaining serial, The Pirate Planet, would not be novelised.
Doctor Who Magazine begins publishing Doctor Who comics written by future comics superstar writer Alan Moore.

6 - Barry Justice (King Charles IX in The Massacre of St Bartholomew's Eve) dies in London.
7 - Final issue of Doctor Who Weekly, which changes to a monthly magazine in September.
21 - Publication Doctor Who and the Keys of Marinus and Doctor Who and the Nightmare of Eden. For the first time in several years, Target Books had released more than one book on the same day.
30 - First episode of The Leisure Hive broadcast, launching a longer-than-usual season that is Tom Baker's final season and the first series produced by John Nathan-Turner. Among the numerous changes evident with this episode is the introduction of a radically different arrangement of the Doctor Who theme by Peter Howell and a new neon-tubing style series logo.

4 - DW:Meglos Episode 2 first broadcast.
11 - DW:Meglos Episode 3 first broadcast.
16 - Publication of Doctor Who and the Horns of Nimon. (Although the series branding has changed to a new logo, the the previous logo is still used by Target Books for several more volumes.
18 - DW:Meglos Episode 4 first broadcast.
25 - DW:Full Circle Episode 1 first broadcast. Matthew Waterhouse debuts as new companion Adric.

1 - Full Circle Episode 2 first broadcast.
8 - DW: Full Circle Episode 3 first broadcast.
13 - Junior Doctor Who and the Brain of Morbius published. This is a short version of Doctor Who and the Brain of Morbius aimed at younger readers and is one of two "Junior Doctor Who" books released in 1980. Reportedly the book was originally to have been released in 1978.
15 - DW:Full Circle Episode 4 first broadcast.
22 - DW:State of Decay Episode 1 first broadcast.
29 - DW:State of Decay Episode 2 first broadcast.

4 - Publication of Doctor Who and the Monster of Peladon.
6 - DW:State of Decay Episode 3 first broadcast.
8 - Ex-Beatle John Lennon, who appeared as himself in The Chase is shot and killed by Mark David Chapman outside his home in New York City.
13 - DW:State of Decay Episode 4 first broadcast.
30 - Tom Baker and Lalla Ward marry; Baker is in the midst of filming The Keeper of Traken, while Ward's final episodes as Romana have yet to be broadcast.

Spring-summer: John Nathan-Turner takes over as Producer of Doctor Who. Among the changes he implements is the introduction of a new arrangement of the theme song by Peter Howell, an updated opening credits sequence, and the announcement that the 1980-81 season will be Tom Baker's last as the Doctor.
Junior Doctor Who and the Giant Robot, a short version of Doctor Who and the Giant Robot aimed at younger readers is published.
The Adventures of K9, a children's book series by David Martin, are published by Sparrow Books.
Tom Baker and Lalla Ward appear as The Doctor and Romana in a series of commercials for Australian television, advertising Prime Computers (an early home microcomputer). While most of the commmercials feature them in their standard character roles, the final commercial in the series has Romana flirting with the Doctor and ends with the Doctor proposing marriage to her!