1983

August

 * 19 - Ianto Jones was born in Newport. (TW: Fragments)

December

 * 10 - The Seventh Doctor, Bernice Summerfield, Roz Forrester, and Chris Cwej arrived in Little Caldwell, England. Bernice Summerfield was reunited with her father. (NA: Return of the Living Dad)
 * 24 - Jason Kane was born. (NA: Return of the Living Dad)

Undated

 * Alistair Gordon Lethbridge-Stewart, now retired and working at Brendon Public School, met the Fifth Doctor and in the ensuing adventure met his younger self from 1977, causing his younger self to lose all memory of the Doctor and experience a breakdown, while his 1983 self regained his memory. Vislor Turlough joined the Doctor on his travels, although unknown to the Doctor, he did so under the orders of the Black Guardian. According to the Brigadier, Harry Sullivan was doing "hush-hush" work on behalf of NATO at this time. (DW: Mawdryn Undead)


 * After the Fifth Doctor departed, the Brigadier reactivated his relationship with UNIT (as suggested by DW: The Five Doctors), eventually returning to active duty (at some point before DW: Battlefield).


 * The Second Doctor and the Brigadier were abducted by Borusa while attending a UNIT reunion. (DW: The Five Doctors)


 * Ace burnt down Gabriel Chase. (DW: Ghost Light)

January

 * 03 - DW: Arc of Infinity Part 1 was first broadcast, launching Doctor Who's 20th season. Future Sixth Doctor Colin Baker made his first appearance on the series, but as a different character.
 * 05 - DW: Arc of Infinity Part 2 was first broadcast.
 * 11 - DW: Arc of Infinity Part 3 was first broadcast.
 * 12 - DW: Arc of Infinity Part 4 was first broadcast.
 * 18 - DW: Snakedance Part 1 was first broadcast.
 * 19 - DW: Snakedance Part 2 was first broadcast.
 * 25 - DW: Snakedance Part 3 was first broadcast.
 * 26 - DW: Snakedance Part 4 was first broadcast.

February

 * 01 - DW: Mawdryn Undead Part 1 was first broadcast. Mark Strickson joined as new companion Vislor Turlough, while Nicholas Courtney made his first appearance as Alistair Gordon Lethbridge-Stewart since Terror of the Zygons. This serial was the first to definitively establish that the current incarnation of the Doctor was the fifth.
 * 02 - DW: Mawdryn Undead Part 2 was first broadcast.
 * 08 - DW: Mawdryn Undead Part 3 was first broadcast.
 * 09 - DW: Mawdryn Undead Part 4 was first broadcast.
 * 15 - DW: Terminus Part 1 was first broadcast.
 * 16 - DW: Terminus Part 2 was first broadcast.
 * 20 - Peter Glaze, who played the City Administrator in DW: The Sensorites and the Brigadier in a Doctor Who parody segment of Crackerjack!, died in Dartford, England.
 * 22 - DW: Terminus Part 3 was first broadcast.
 * 23 - DW: Terminus Part 4 was first broadcast. Sarah Sutton left the series with this part.

March

 * Filming and studio recording for DW: The Five Doctors occured this month.
 * REF: The Doctor Who Technical Manual was first published.
 * 01 - DW: Enlightenment Part 1 was first broadcast.
 * 02 - DW: Enlightenment Part 2 was first broadcast.
 * 08 - DW: Enlightenment Part 3 was first broadcast.
 * 09 - DW: Enlightenment Part 4 was first broadcast.
 * 15 - DW: The King's Demons Part 1 was first broadcast. Introduction of the android companion Kamelion.
 * 16 - DW: The King's Demons Part 2 was first broadcast, technically concluding Season 20, although the later special DW: The Five Doctors will also be considered part of Season 20.
 * 21 - Bruno Langley, who portrayed companion Adam Mitchell in 2005, was born in Devon, England.

April

 * 15 - DWN: Doctor Who - Time-Flight was first published.

May

 * 02 - 10th anniversary of the launch of Target Books' line of Doctor Who novelisations.
 * 05 - DWN: Doctor Who - Meglos was first published. This was the final televised Fourth Doctor story to be novelised. Due to licensing issues, no novelisations were ever officially published for DW: The Pirate Planet, DW: City of Death or the unfinished/unbroadcast DW: Shada. Target Books would publish one more Fourth Doctor novelisation, DWN: The Pescatons, based upon an audio drama, in 1991.

June

 * 16 - DWN: Doctor Who - Castrovalva was first published.
 * 23 - Publication of Doctor Who: Daleks Omnibus, a hardcover Target Books collection reprinting the Terrance Dicks novelisations DWN: Doctor Who and the Dalek Invasion of Earth, DWN: Doctor Who and the Day of the Daleks and DWN: Doctor Who and the Planet of the Daleks.

July

 * 21 - DWN: Doctor Who - Four to Doomsday was first published.

August

 * The BBC announced that Colin Baker - no relation to Tom Baker - had been cast as the Sixth Doctor.
 * Doctor Who Annual 1984 was published.
 * 18 - DWN: Doctor Who - Earthshock was first published.

September

 * 13 - REF: Doctor Who: A Celebration was first published.
 * 15 - DWN: Doctor Who - Terminus was first published.

October

 * REF: Doctor Who: The Making of a Television Series was published in paperback.
 * 14-19 Filming for DW: Planet of Fire took place in Lanzarote, Canary Islands, marking the first time Doctor Who was filmed outside the European continent.
 * 20 - DWN: Doctor Who - Arc of Infinity was first published.

November

 * REF: Doctor Who: The Unfolding Text, one of the first widely published scholarly works on the franchise, was first published in both the UK and US.
 * 02 - Michael Spice, who played Morbius in DW: The Brain of Morbius and Magnus Greel in DW: The Talons of Weng-Chiang, died.
 * 19 - For the first time in nearly 10 years, Doctor Who made the cover of the Radio Times. It was another decade before this happened again, making this the last Radio Times cover to be published during the original series' run.
 * 23 - 20th anniversary of the first broadcast of Doctor Who.
 * DW: The Five Doctors was broadcast for the first time. However, PBS affiliates in the United States (which are also received on cable television in Canada) broadcast it before the BBC, the first time America saw a Doctor Who story before the UK. This version was slightly truncated compared to the version shown two days later in the UK. This was the first "feature-length" regular Part of Doctor Who produced. The special featured the return of Patrick Troughton and Jon Pertwee (with Tom Baker represented by footage from the unbroadcast DW: Shada). Richard Hurndall made his first and only appearance as the First Doctor. Numerous companions from all eras of the series appeared. Although broadcast closer to the start of Season 21, it was considered part of the anniversary Season 20 and, thus, its belated finale.
 * 24 - DWN: Doctor Who - The Five Doctors was first published. This was the first time a Target Books novelisation has been published before the UK broadcast premiere of an Part. According to the 2008 DVD release of DW: The Five Doctors, this was widely believed to have been an error.
 * 25 - DW: The Five Doctors was first broadcast in the UK, as part of that year's Children in Need fund-raising drive.

Unknown date

 * Magnet Books, a subsidiary of Methuen Children's Books, published Doctor Who Quiz Book of Science, Doctor Who Quiz Book of Space and Doctor Who Quiz Book of Magic, all by Michael Holt, the remainder of the Doctor Who Quiz Book line. These illustrated paperback books (published in the same format as Target Books novelisations) contained original short stories featuring the Fifth Doctor, Nyssa and Tegan Jovanka that set up short quizzes related to the subject matter of the book. The first book in the series had been published in 1982.