31 December

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. (TV: Children of Earth: Day One)
 * 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's TARDIS materialised in a San Francisco alley due to a timing malfunction. 's remains had broken out of a locked chest and tampered with its controls. At the same time, a Chinese-American gang war erupted in the streets. The Seventh Doctor casually walked out of the TARDIS without knowing what was outside, causing the gang members to shoot him. Chang Lee survived the shooting unharmed and helped get the wounded Doctor to a hospital. The bullets were removed from his body, but his Time Lord physiology confounded human surgeon Grace Holloway, which led to exploratory surgery that accidentally killed the Seventh Doctor and her firing. Inside a morgue, he regenerated into his eighth incarnation, forced his way out, and discovered his memories were gone due. The Master's remains escaped and took Bruce as a host. The Doctor tried to convince Grace he was the same man as before and recruited her to help him with his bout of amnesia, eventually regaining them. Meanwhile, Chang Lee had pocketed the Doctor's key to the TARDIS and began raiding it. However, the Master found Chang Lee, manipulated him to open the Eye of Harmony. The Doctor found his way back to the TARDIS, getting inside with a spare key. The Master opened the Eye and the Earth started to fluctuate, leading to the temporary deaths of Grace and Chang Lee. The Doctor closed the Eye and the Master was consumed by it, reversing the deaths of the two humans. (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. He had been driven insane by a psychic locket that showed him dark things awaiting in the future. Hopkins tricked Jack to leave the Hub because he was immortal and would have prevented Hopkins' "mercy killings." Harkness subsequently took over Torchwood Three, given the leadership by Alex just before he claimed his own life. (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)
 * 1999 - "Dara Morgan" suddenly came to being, and registered MorganTech. He was broadcast live on a news channel that same day. (PROSE: Beautiful Chaos)
 * 2007 - The Eighth Doctor and Charley Pollard arrived at 8:00, and witnessed New Year's Eve. They had intended to go to 1931, Charley's time, as she wanted to leave. The TARDIS had brought them to the wrong time because of a time hump on 17 January 1942. (AUDIO: The Girl Who Never Was)
 * 2066 - Jack Harkness visited a bar on Zog. There, an individual of an unnamed species gave him instructions for the either earlier or later version of him. This version, upon opening a box on 7 August 1941, relived these experiences. (COMIC: Overture)
 * 2599 - A New Year's party at the Braxiatel Collection was interrupted by murder. (PROSE: The Doomsday Manuscript)