31 December

 was the final day of December when many Earth-based cultures celebrated New Year's Eve.

Amongst the notable things that occurred on this day were:
 * 1879 - Queen Victoria issued the Torchwood Charter and founded the Torchwood Institute.
 * 1899 - The Torchwood One agent Gerald Kneale assisted Torchwood Three with the Centurian Incident and its clean-up in Cardiff. (COMIC: Rift War! Part Six: Circles)
 * 1926 - The Marylebone Cricket Club (MCC) played All India in the 2nd Unofficial Test match of the scene in Calcutta, British India. The MCC won the match by four wickets. The Fifth Doctor considered it to be one of the best cricket matches of all time. (AUDIO: The Emerald Tiger)
 * 1930 - The Eighth Doctor and his companion Charley Pollard celebrated New Year's Eve in Singapore. (AUDIO: Seasons of Fear)
 * 1999 - The Seventh Doctor regenerated into his eighth incarnation. The Master took Bruce as a host. The Master opened the Eye of Harmony and the Earth started to fluctuate. The Doctor closed the Eye and the Master was consumed by it. (TV: Doctor Who)
 * 1999 - The Sixth Doctor and Melanie Bush saved the Earth from being taken over by Saraquazel, a being from the After-Universe, and his servant Ashley Chapel. (PROSE: Millennial Rites)
 * 1999 - A younger version of the Seventh Doctor and an older version of Mel gate crashed the New Year's Eve party being thrown by Alisha Hammerson, the Auton head of Hammerson Plastic PLC, in London. They foiled her plan to replace her guests with Auton replicas so the Earth could be dominated and absorbed by severing her link to the Nestene Consciousness. (COMIC: Plastic Millennium)
 * 1999 - The Fourth Doctor stopped the millennium bug as the New Year arrived. (PROSE: Millennium Shock)
 * 1999 - While Jack Harkness fought a "Millennium Bug" of his own, Alex Hopkins killed the rest of his Torchwood Three team, then himself after Jack returned, just as the New Year arrived in Cardiff's time zone. Harkness subsequently took over Torchwood Three (TV: Fragments)
 * 1999 - Dave Young spent the entire evening trying to convince his girlfriend, Anji Kapoor, that the millennium wouldn't actually begin for another year. Kapoor, for her part, thought this extreme pedantry meant their relationship was in trouble. This incident led to her insisting on New Year's Eve 2000 that the two of them spend 2001 doing "Wild and Spontaneous Things' — the result of which was the couple spontaneously going to Belgium in February 2001. There, she met the Eighth Doctor and began travelling with him. (PROSE: Escape Velocity)
 * 1999 - The renegade Time Lady Iris Wildthyme and her companion Panda arrived in San Francisco in her TARDIS. Immediately after their arrival, Iris spilled gin into the bus' control and out into Time Vortex, resulting in various different versions of Panda from alternative realities crossing over into the primary universe. With the assistance of Dr. George Strangeways, Iris was able to close the rift, though not before the Panda from the primary universe had been dragged into it. (AUDIO: The Panda Invasion)
 * 2599 - A New Years' party at the Braxiatel Collection was interrupted by murder. (PROSE: The Doomsday Manuscript)

Behind the scenes

 * 1927 - Actor Frank Gatliff was born.
 * 1966 - Episode three of The Highlanders was first broadcast on BBC1.