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 - 20) - The events of The War Machines take place.
 * 20 - The events of The Faceless Ones and the opening of The Evil of the Daleks take place.

September

 * 8 - The science fiction TV series Star Trek broadcasts for the first time in America, spawning a long-lasting entertainment franchise that would impact a number of the Doctor's companions, including Rose Tyler, who dubs the Ninth Doctor "Mr. Spock" (DW: The Empty Child) and Donna Noble, who would briefly adopt the alias "Captain Kirk" during an adventure, with the Tenth Doctor calling himself Dr. McCoy. (Pest Control).

November

 * 15 - Perpugilliam Brown is born in America.

Unknown date

 * The events of The Veiled Leopard take place.
 * The TARDIS lands on the Empire State Building. (DW: The Chase)
 * The events of The Love Invasion take place.

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)
 * 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)

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
 * 25 - The War Machines Episode 1 First Broadcast

July

 * 02 - The War Machines Episode 2 First Broadcast
 * 09 - The War Machines Episode 3 First Broadcast
 * 16 - The War Machines Episode 4 First Broadcast

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.

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
 * 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
 * 24 - The Highlanders Episode 2 First Broadcast
 * 31 - The Highlanders Episode 3 First Broadcast

Reference

 * A History of the Universe by Lance Parkin