1975

December

 * 24 - The Seventh Doctor and his companions Ace and Hex defeated the Kellenian invasion of Earth in New York City. (ST: Presence)

Unknown dates

 * Toshiko Sato was born. (TW: Greeks Bearing Gifts)

January to April

 * The stage play SP: Doctor Who and the Daleks in The Seven Keys to Doomsday toured the UK.

January

 * DWN: Doctor Who and the Curse of Peladon was first published.
 * 4 - DW: Robot Episode 2 was first broadcast.
 * 11 - DW: Robot Episode 3 was first broadcast.
 * 16 - The BBC's Audience Research Dept. filed an Audience Research Report on DW: Robot Episode 1. The episode received a Reaction Index of 53. Reaction to new Doctor Tom Baker was mixed, with some respondents saying he would take some getting used to.
 * 18 - DW: Robot Episode 4 was first broadcast. Although there were two more UNIT stories over the next year, this episode marked the end of the Doctor's continuous involvement with UNIT.
 * 24 - Neil Wilson (Sam Seeley in DW: Spearhead from Space) died.
 * 25 - DW: The Ark in Space Episode 1 was first broadcast.

February

 * 01 - DW: The Ark in Space Episode 2 was first broadcast.
 * 08 - DW: The Ark in Space Episode 3 was first broadcast.
 * 15 - DW: The Ark in Space Episode 4 was first broadcast.
 * 20 - DWN: Doctor Who and the Cybermen was first published.
 * 22 - DW: The Sontaran Experiment Episode 1 was first broadcast.

March

 * 01 - DW: The Sontaran Experiment Episode 2 was first broadcast.
 * 08 - DW: Genesis of the Daleks Episode 1 was first broadcast. This was the first appearance of Davros.
 * 10 - Yee Jee Tso, who portrayed Chang Lee in the 1996 Doctor Who television movie, was born.
 * 13 - DWN: Doctor Who and the Giant Robot was first published. It was the first novelisation of a Fourth Doctor serial and the first novelisation to be published during the same TV season in which the adapted serial (DW: Robot) was actually broadcast.
 * 15 - DW: Genesis of the Daleks Episode 2 was first broadcast.
 * 22 - DW: Genesis of the Daleks Episode 3 was first broadcast.
 * 29 - DW: Genesis of the Daleks Episode 4 was first broadcast.

April

 * 05 - DW: Genesis of the Daleks Episode 5 was first broadcast.
 * 12 - DW: Genesis of the Daleks Episode 6 was first broadcast.
 * 19 - DW: Revenge of the Cybermen Episode 1 was first broadcast.
 * 23 - William Hartnell, the first actor to portray the Doctor, died in Marden, Kent, England. Hartnell has the sad distinction of being the first major, ongoing cast member of Doctor Who to pass away.
 * 26 - DW: Revenge of the Cybermen Episode 2 was first broadcast.
 * 26 - Kevin Lindsay, who guested several times on Doctor Who, died.

May

 * 03 - DW: Revenge of the Cybermen Episode 3 was first broadcast.
 * 10 - DW: Revenge of the Cybermen Episode 4 was first broadcast, bringing Season 12 to a premature end following the BBC's decision to reschedule the originally planned season finale, DW: Terror of the Zygons, to the start of Season 13.
 * 15 - DWN: Doctor Who and the Terror of the Autons was first published.

June

 * 16 - Fred Koehler (Ralph Coltrane in TW: The Categories of Life and TW: The Middle Men) was born.

July

 * 15 - Raf De La Torre, who played the senior judge in DW: The Keys of Marinus, died.

August

 * 21 - DWN: Doctor Who and the Green Death was first published.
 * 23 - Tom Baker presented Disney Time in character as the Fourth Doctor
 * 30 - DW: Terror of the Zygons Episode 1 was first broadcast, opening Season 13 and marking the first autumn start for a Doctor Who season since 1968-69. The serial was originally intended to end Season 12, but was pushed back to make a fall season start feasible.

September

 * Doctor Who Annual 1976 was published.
 * Terry Nation's Dalek Annual 1976 was published
 * 06 - DW: Terror of the Zygons Episode 2 was first broadcast.
 * 13 - DW: Terror of the Zygons Episode 3 was first broadcast.
 * 20 - DW: Terror of the Zygons Episode 4 was first broadcast. Ian Marter left the series as a regular with this episode, although he returned a few weeks later in DW: The Android Invasion in a guest appearance. This was also Nicholas Courtney's final regular appearance as Brigadier Alistair Gordon Lethbridge-Stewart; he next played the character in the 1983 serial DW: Mawdryn Undead. Although UNIT returned in The Android Invasion and the Doctor was on a UNIT mission in DW: The Seeds of Doom, this, the last appearance of the Brigadier, marked this as the official end of the UNIT era.
 * 24 - Clive Morton (George Trenchard in DW: The Sea Devils) died.
 * 27 - DW: Planet of Evil Episode 1 was first broadcast.

October

 * 04 - DW: Planet of Evil Episode 2 was first broadcast.
 * 11 - DW: Planet of Evil Episode 3 was first broadcast.
 * 16 - DWN: Doctor Who and the Planet of the Spiders was first published.
 * 18 - DW: Planet of Evil Episode 4 was first broadcast.
 * 24 - Martin Boddey (Walker in DW: The Sea Devils) died.
 * 25 - DW: Pyramids of Mars Episode 1 was first broadcast.

November

 * 01 - DW: Pyramids of Mars Episode 2 was first broadcast.
 * 08 - DW: Pyramids of Mars Episode 3 was first broadcast.
 * 15 - DW: Pyramids of Mars Episode 4 was first broadcast.
 * 20 - DWN: Doctor Who - The Three Doctors was first published. It was the first novelisation not to use the title form Doctor Who and the .... This was also the first Target Books-commissioned novelisation to feature the First Doctor.
 * 20 - The Doctor Who Monster Book was first published.
 * 22 - DW: The Android Invasion Episode 1 was first broadcast.
 * 29 - DW: The Android Invasion Episode 2 was first broadcast.

December

 * 06 - DW: The Android Invasion Episode 3 was first broadcast.
 * 06 - Noel Clarke, who played Mickey Smith in the revived Doctor Who, was born.
 * 13 - DW: The Android Invasion Episode 4 was first broadcast. It was the final appearances of Ian Marter as Harry Sullivan, John Levene as John Benton and, as a regular part of the series, UNIT. After this episode the series went on a brief hiatus for Christmas.

Unknown

 * Anna-Louise Plowman, who played Diana Goddard in DW: Dalek, was born.
 * Dean Lennox Kelly, who played William Shakespeare in DW: The Shakespeare Code, was born.