1966

January

 * 1 - The TARDIS departs Trafalgar Square, where it had arrived during the New Year's Eve celebrations. (DW: The Daleks' Master Plan)

July

 * 5 - Ben Jackson begins a five month shore posting. (DW: The War Machines)
 * 12 through 20 - From its base in the Post Office Tower in London, WOTAN directs both mind controlled Humans and robot War Machines. (DW: The War Machines)
 * 20 - The Doctor, Polly, Ben Jackson and Jamie McCrimmon get involved with the schemes of the Chameleons at Gatwick Airport. Ben and Polly decide to stay behind in their own time. (DW: The Faceless Ones) Meanwhile, the Daleks steal the TARDIS. (DW: The Evil of the Daleks)

November

 * 15 - Birth of Peri Brown, companion of the the Doctor in his fifth and sixth incarnations. (DW: Planet of Fire)

Unknown date

 * The Doctor and Rose Tyler visit London (DWM: The Love Invasion)
 * Ace and Hex meet Peri Brown and Erimem (BFA: The Veiled Leopard)

January

 * 01 - "Volcano" First Broadcast (The Daleks' Master Plan Episode 8)
 * 08 - "Golden Death" First Broadcast (The Daleks' Master Plan Episode 9)
 * 15 - "Escape Switch" First Broadcast (The Daleks' Master Plan Episode 10)
 * 22 - "The Abandoned Planet" First Broadcast (The Daleks' Master Plan Episode 11)
 * 29 - "Destruction of Time" First Broadcast (The Daleks' Master Plan Episode 12). Jean Marsh leaves the series as her character, Sara Kingdom, becomes the second companion to die in the line of duty.
 * 30 - Daphne Ashbrook is born in Long Beach, California.

February

 * 05 - "War of God" First Broadcast (The Massacre of St Bartholomew's Eve Episode 1)
 * 12 - "The Sea Beggar" First Broadcast (The Massacre of St Bartholomew's Eve Episode 2)
 * 19 - "Priest of Death" First Broadcast (The Massacre of St Bartholomew's Eve Episode 3)
 * 26 - "Bell of Doom" First Broadcast (The Massacre of St Bartholomew's Eve Episode 4). Jackie Lane makes her debut as companion Dodo Chaplet.

March

 * 05 - "The Steel Sky" First Broadcast (The Ark Episode 1)
 * 12 - "The Plague" First Broadcast (The Ark Episode 2)
 * 19 - "The Return" First Broadcast (The Ark Episode 3)
 * 26 - "The Bomb" First Broadcast (The Ark Episode 4)

April

 * 02 - "The Celestial Toyroom" First Broadcast (The Celestial Toymaker Episode 1)
 * 09 - "The Hall of Dolls" First Broadcast (The Celestial Toymaker Episode 2)
 * 16 - "The Dancing Floor" First Broadcast (The Celestial Toymaker Episode 3)
 * 23 - "The Final Test" First Broadcast (The Celestial Toymaker Episode 4)
 * 30 - "A Holiday for the Doctor" First Broadcast (The Gunfighters Episode 1)

May

 * 07 - "Don't Shoot the Pianist" First Broadcast (The Gunfighters Episode 2)
 * 14 - "Johnny Ringo" First Broadcast (The Gunfighters Episode 3)
 * 21 - "The OK Corral" First Broadcast (The Gunfighters Episode 4). This marks the final time individual episode titles would be used in the original series (the practice would resume in 2005).
 * 28 - The Savages Episode 1 First Broadcast

June

 * 04 - The Savages Episode 2 First Broadcast
 * 11 - The Savages Episode 3 First Broadcast
 * 18 - The Savages Episode 4 First Broadcast. Peter Purves leaves the series with this episode, although he would continue his association with Doctor Who for years to come when he subsequently becomes co-host of Blue Peter.
 * 25 - The War Machines Episode 1 First Broadcast. Michael Craze and Anneke Wills make their debuts as Ben Jackson and Polly, respectively. This episode is notorious for having a character -- the computer WOTAN -- break the longstanding taboo of referring to the Doctor by the name "Doctor Who".

July

 * 02 - The War Machines Episode 2 First Broadcast. Final appearance of Jackie Lane as Dodo Chaplet.
 * 09 - The War Machines Episode 3 First Broadcast
 * 16 - The War Machines Episode 4 First Broadcast
 * The film Dr. Who and the Daleks is released to theatres in the United States.

Summer

 * William Hartnell sends shockwaves through the Doctor Who production team by announcing his intention to leave the series. The producers and writers develop the concept of regeneration to explain the change of lead actor and cast Patrick Troughton as the new Doctor; Hartnell agrees to appear in the first two serials of the new season.

August

 * 05 - The second feature film, Daleks - Invasion Earth 2150 AD is released in the UK.

September

 * 8 - Star Trek debuts in America. This influential series would go on to become Doctor Who's chief rival in terms of franchise longevity, although the original series would only run until the spring of 1969.
 * 10 - The Smugglers Episode 1 First Broadcast
 * 17 - The Smugglers Episode 2 First Broadcast
 * 24 - The Smugglers Episode 3 First Broadcast

October

 * 01 - The Smugglers Episode 4 First Broadcast
 * 08 - The Tenth Planet Episode 1 First Broadcast
 * 08 - Camille Coduri who plays Jackie Tyler in series 1, 2 and (as a one off appearance) 4 of the revived Doctor Who is born in Wandsworth London.
 * 15 - The Tenth Planet Episode 2 First Broadcast
 * 22 - The Tenth Planet Episode 3 First Broadcast
 * 29 - The Tenth Planet Episode 4 First Broadcast, ending in the first regeneration, from William Hartnell to Patrick Troughton

November

 * 05 - The Power of the Daleks Episode 1 First Broadcast
 * 12 - The Power of the Daleks Episode 2 First Broadcast
 * 19 - The Power of the Daleks Episode 3 First Broadcast
 * 26 - The Power of the Daleks Episode 4 First Broadcast

December

 * 03 - The Power of the Daleks Episode 5 First Broadcast
 * 10 - The Power of the Daleks Episode 6 First Broadcast
 * 17 - The Highlanders Episode 1 First Broadcast. Frazer Hines debuts as new companion Jamie McCrimmon.
 * 24 - The Highlanders Episode 2 First Broadcast
 * 31 - The Highlanders Episode 3 First Broadcast

Reference

 * A History of the Universe by Lance Parkin