1986

History of the Doctor Who Universe
By this year International Space Command had regular Lunar flights and maintained a tracking station in Antarctica (DW: The Tenth Planet)

December
Humans first detect the Planet Mondas returning to the solar system, while it apparently was in orbit between Mars and Venus. The manned atmospheric probe Zeus IV is destroyed by the Cybermen inhabitants, and they go on to launch an attack on the Earth, starting with the Snowcap base in Antarctica. They plan to use a Z-bomb located here to destroy the Earth as one of their two worlds needed to be destroyed to save the other, but when they fail, Mondas is destroyed instead. Present for these events is the Doctor, and while the Cybermen are defeated, the strain of the conflict leads to his subsequent regeneration from his first incarnation into his second. (DW: The Tenth Planet)

Unknown date

 * Pete Tyler and Jackie Tyler marry. The event is witnessed secretly by their future daughter Rose Tyler and the Doctor. (DW: Father's Day)
 * Approximate year of the events of Harry Sullivan's War. Based upon the book's publishing date, coupled with statements that it takes place 10 years after The Android Invasion, established as taking place circa 1976.''

January

 * 09 - Doctor Who - The Gunfighters First Published.

February

 * 13 - Doctor Who - The Time Monster First Published.


 * 22 - Donald Eccles (Krasis in The Time Monster) is killed in a road accident in Brighton, England, UK.

March

 * 13 - Doctor Who - The Twin Dilemma First Published.

April

 * 10 - Doctor Who - Galaxy Four First Published.

May

 * 15 - Doctor Who - Timelash and Turlough and the Earthlink Dilemma First Published. Turlough and the Earthlink Dilemma is the first release of a planned spin-off series of original novels called "The Companions of Doctor Who". As such, this book is the first original novel based upon characters from the TV series (discounting shorter works released in annuals).
 * 24 - Robert Holmes, widely considered one of Doctor Who's best scriptwriters, dies. His last work was episode 13 of The Trial of a Time Lord, aka episode 1 of The Ultimate Foe.
 * Around the time of Holmes' death, Eric Saward resigns as script editor due to a disagreement with John Nathan-Turner over Saward and Holmes' plans for the final episode of the Trial story arc; Nathan-Turner commissions Pip and Jane Baker to write the final chapter.

June

 * 11 - Reed De Rouen, who played Pa Clanton in "The Gunfighters," dies.


 * 12 - Doctor Who - The Mark of the Rani First Published.

July

 * 10 - Doctor Who - The King's Demons First Published.

August

 * 21 - Doctor Who - Slipback First Published. Adapted from the radio play of the same name, this is the first novelisation of a Doctor Who story not produced for television.

September

 * 06 - The Mysterious Planet Episode 1 First Broadcast (The Trial of a Time Lord Episode 1). The series returns to its original 25-minute episode format and the number of episodes per season is increased from 13 to 14. However, given the actual episode length reverted back to 25 minutes, this has resulted in a considerably shortened season in comparison to the 1984 and previous seasons. Trial of a Time Lord, although not the first season to consist of a single story arc (see The Key to Time), this is the first time only one on-screen title would be used for the entire season, although the fanbase and producers would divide the tale into four stories. A new arrangment of the theme music, by Dominic Glynn, is introduced.


 * 11 - Doctor Who - The Savages and Harry Sullivan's War First Published. Harry Sullivan's War is the second of three releases under the Companions of Doctor Who spin-off line, and is written by Ian Marter, who also portrayed Harry Sullivan in the TV series more than a decade earlier. Marter died a few weeks later, making this the final book released (but not the final book written) in his lifetime.


 * 13 - The Mysterious Planet Episode 2 First Broadcast (The Trial of a Time Lord Episode 2)


 * 20 - The Mysterious Planet Episode 3 First Broadcast (The Trial of a Time Lord Episode 3)


 * 27 - The Mysterious Planet Episode 4 First Broadcast (The Trial of a Time Lord Episode 4)

October

 * 04 - Mindwarp Episode 1 First Broadcast (The Trial of a Time Lord Episode 5)


 * 11 - Mindwarp Episode 2 First Broadcast (The Trial of a Time Lord Episode 6)


 * 16 - Doctor Who - Fury from the Deep First Published. Promoted as a "bumper volume" due to a higher word count than most Target Books releases up to this time.


 * 18 - Mindwarp Episode 3 First Broadcast (The Trial of a Time Lord Episode 7)


 * 25 - Mindwarp Episode 4 First Broadcast (The Trial of a Time Lord Episode 8). Nicola Bryant leaves the series with this episode.


 * 28 - Ian Marter, who played companion Harry Sullivan and also wrote numerous novelisations for Target Books, dies from a diabetes-related heart attack in London.

November

 * 01 - Terror of the Vervoids Episode 1 First Broadcast (The Trial of a Time Lord Episode 9). Debut of Bonnie Langford as Melanie Bush.


 * 08 - Terror of the Vervoids Episode 2 First Broadcast (The Trial of a Time Lord Episode 10)


 * 15 - Terror of the Vervoids Episode 3 First Broadcast (The Trial of a Time Lord Episode 11)


 * 20 - Doctor Who - The Celestial Toymaker First Published.


 * 22 - Terror of the Vervoids Episode 4 First Broadcast (The Trial of a Time Lord Episode 12)


 * 29 - The Ultimate Foe Episode 1 First Broadcast (The Trial of a Time Lord Episode 13). This is the final episode to carry a writer credit for the late Robert Holmes, and is also the last episode to credit Eric Saward as script editor.

December

 * 04 - Doctor Who - The Seeds of Death First Published.


 * 06 - The Ultimate Foe Episode 2 First Broadcast (The Trial of a Time Lord Episode 14). Although not widely known at the time, this would be Colin Baker's final appearance in the series. This also marked the final use of Dominic Glynn's short-lived theme arrangement and the neon-tubing series logo that had been in place (with adjustments upon Baker's arrival) since 1980.

Unknown date

 * John Flint, who played William des Preaux in "The Crusade" and Captain Urquhart in "Time-Flight," dies.