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On 21 December, a number of things set in or relevant to the Doctor Who universe were released or published.
- You may be looking for the event in the DWU.
- 1963 - "The Dead Planet" was first broadcast on BBC tv.
- 1964 - Part seven of the TV Comic story The Klepton Parasites was first published.
- 1965 - The stage play The Curse of the Daleks premièred at Wyndham's Theatre. The short story The Daleks was released as a tie-in.
- 1968 - Episode eight of The Invasion was first broadcast on BBC1.
- 1968 - Part four of the TV Comic story Jungle of Doom was first published.
- 1974 - Part three of the TV Comic story The Wanderers was first published.
- 1988 - Part two of The Greatest Show In The Galaxy was first broadcast on BBC1.
- 1989 - The novelisation of The Greatest Show in the Galaxy was first released by Target Books.
- 1989 - The Doctor Who Programme Guide was reissued as a single-volume, expanded and revised edition.
- 1995 - DWM 234 was first released by Marvel Comics.
- 1996 - Part ten of the Radio Times comic story Ascendance was first published.
- 2010 - The audiobook version of The Little Drummer Boy was first released to Big Finish subscribers.
- 2010 - Charlie McDonnell - Runner was first broadcast on the BBC Red Button service and released online on the BBC YouTube channel.
- 2011 - Part two of Attack of the Snowmen was first published online.
- 2011 - DWMI 17 was first published by Immediate Media Company London Limited.
- 2012 - Songtaran Carols was first released online.
- 2012 - The Brit List: The Doctor Who Ultimate List of Lists was first broadcast on BBC America.
- 2014 - Part three of Behind You was first published online.
- 2014 - Toby Hadoke's Who's Round 98 was released by Big Finish.
- 2015 - Part one of Haunted was first published online.
- 2016 - 9DO 8, 10DY2 17 and 11DY2 15 were first released by Titan Comics.
- 2017 - Doctor Who and the Horror of Coal Hill was first released online.
- 2017 - Toby Hadoke's Who's Round 231 was released by Big Finish.
- 2018 - The Devil's Footprints was first released by Big Finish.
- 2020 - Incoming Transmission was first released online.
- 2025 - The End of the War was first broadcast on BBC One, concluding The War Between the Land and the Sea.