21 January (releases)

* 1967 - Episode two of The Underwater Menace was first broadcast on BBC1.
* 1967 - Part one of the TV Comic story The Trodos Ambush was first published.
* 1978 - Part three of Underworld was first broadcast on BBC1.
* 1978 - Part two of the TV Comic story The Snow Devils was first published.
* 1988 - The novelisation of The Rescue was first released in paperback by Target Books.
* 1993 - DWM 196 was first released by Marvel Comics.
* 2002 - The audio story Project: Infinity was released by Big Finish Productions.
* 2007 - Immortal Beloved was broadcast on BBC7.
* 2009 - The Doctor Who: Battles in Time comic story Metal Mania was first published.
* 2009 - TF 6 was first published by IDW Publishing.
* 2010 - Doctor Who at the BBC: A Legend Reborn was first released by BBC Audio.
* 2010 - DWA 150 was first released by BBC Magazines.
* 2010 - A Thousand Tiny Wings and Leviathan were first released by Big Finish.
* 2020 - Dark Universe was first released by Big Finish.
* 2021 - 24 Carat was first released on the official Doctor Who YouTube channel.