1970

January

 * A part-Time Lord part-human girl regenerated into what would later be known as Mels. (DW: Day of the Moon, DW: A Good Man Goes to War / Let's Kill Hitler)

August

 * 20 - Dorothy Gale McShane, who would later be a companion of the Seventh Doctor (and known as "Ace"), was born to Audrey Dudman in England. (DW: Ghost Light)

December

 * Mars Probe 7 reached Earth. The radioactive aliens were removed. The Third Doctor prevented Carrington from starting a war. (DW: The Ambassadors of Death)  on date

Unknown dates

 * "Mary" killed Myra Bennett to consume her heart. Human authorities did not manage to catch her. (TW: Greeks Bearing Gifts)

January

 * 3 - DW: Spearhead from Space Episode 1, the first colour episode of Doctor Who, the first of Season 7, and the first starring Jon Pertwee as the Third Doctor was first broadcast. It launched the "UNIT era" of the series. Beginning in 1970, the number of episodes produced each season was reduced considerably, and the show moved from a Fall to Spring broadcast schedule to a January-June schedule. Caroline John debuted as companion Liz Shaw, while Nicholas Courtney, as Brigadier Alistair Gordon Lethbridge-Stewart, became a series regular with this episode.
 * 10 - DW: Spearhead from Space Episode 2 was first broadcast.
 * 17 - DW: Spearhead from Space Episode 3 was first broadcast.
 * 24 - DW: Spearhead from Space Episode 4 was first broadcast.
 * 29 - Jon Pertwee discussed the Third Doctor’s new car, Bessie, in the pages of Radio Times.
 * 31 - DW: Doctor Who and the Silurians Episode 1 was first broadcast. The Doctor's car, Bessie, appeared for the first time. This was the only televised story to use the Doctor Who and the ... title format. This occurred as a result of a clerical error.

February

 * 7 - DW: Doctor Who and the Silurians Episode 2 was first broadcast.
 * 14 - DW: Doctor Who and the Silurians Episode 3 was first broadcast.
 * 21 - DW: Doctor Who and the Silurians Episode 4 was first broadcast.
 * 27 - The BBC's Audience Research Dept. filed an Audience Research Report on DW: Spearhead from Space Episode 1. The episode rates a Reaction Index of 54, with new Doctor Jon Pertwee having been "accepted without question".
 * 28 - DW: Doctor Who and the Silurians Episode 5 was first broadcast.

March

 * 7 - DW: Doctor Who and the Silurians Episode 6 was first broadcast.
 * 14 - DW: Doctor Who and the Silurians Episode 7 was first broadcast.
 * 21 - DW: The Ambassadors of Death Episode 1 was first broadcast.
 * 28 - DW: The Ambassadors of Death Episode 2 was first broadcast.

April

 * 4 - DW: The Ambassadors of Death Episode 3 was first broadcast.
 * 11 - DW: The Ambassadors of Death Episode 4 was first broadcast.
 * 18 - DW: The Ambassadors of Death Episode 5 was first broadcast.
 * 25 - DW: The Ambassadors of Death Episode 6 was first broadcast. First UNIT-era appearance of John Levene as Sgt. Benton, who becames a semi-regular for the next six years.

May

 * 2 - DW: The Ambassadors of Death Episode 7 was first broadcast.
 * 9 - DW: Inferno Episode 1 was first broadcast.
 * 16 - DW: Inferno Episode 2 was first broadcast.
 * 23 - DW: Inferno Episode 3 was first broadcast.
 * 30 - DW: Inferno Episode 4 was first broadcast.

June

 * 6 - DW: Inferno Episode 5 was first broadcast.
 * 13 - DW: Inferno Episode 6 was first broadcast.
 * 20 - DW: Inferno Episode 7 was first broadcast, concluding Season 7, which was the shortest season to date and the shortest-ever season in terms of number of serials until Season 23's single-story marathon. Caroline John left the series after this episode.

July

 * 10 - John Simm was born.

August

 * 3 - Elizabeth Berrington was born.

September

 * Publication of the sixth Doctor Who Annual.

October

 * 05 - In the US, the National Educational Television network was rebranded and relaunched as the Public Broadcasting Service (PBS). This loose affiliation of broadcasters would introduce countless UK-produced television programs to North American audiences over the next four decades, and became the primary broadcast home of the 1963-89 version of Doctor Who beginning in the late 1970s.

November

 * 06 - Colin Baker made his TV acting debut in an episode of The Adventures of Don Quick.