- Dec 1 Gasoline rationed in US
- Dec 1 The Beveridge Report is published by the British government unveiling plans for a post-war welfare state
- Dec 1 With WWII travel restrictions in mind, MLB owners decide to restrict travel to a 3-trip schedule rather than customary 4; Spring training in 1943 limited to locations north of Potomac or Ohio rivers and east of the Mississippi
Nuclear Chain Reaction
Dec 2 World’s 1st self-sustaining nuclear chain reaction occurs in Chicago Pile-1 (world's 1st nuclear reactor) at the University of Chicago, overseen by Enrico Fermi and Leó Szilárd
- Dec 4 First US citizenship granted to an alien on foreign soil (James Hoey)
- Dec 4 Holocaust: In Warsaw, Zofia Kossak-Szczucka and Wanda Filipowicz set up the Żegota organization
- Dec 4 US bombers strike Italian mainland for first time in WW II
- Dec 5 CFL Grey Cup, Varsity Stadium, Toronto: Toronto RCAF Hurricanes beat Winnipeg RCAF Bombers, 8-5
- Dec 5 Seyss-Inquart orders students in nazi-Germany to work
- Dec 5 West Indies chocolate/coffee drop above Netherland
Dutch Commonwealth Begins
Dec 6 Queen Wilhelmina announces Dutch Commonwealth
Hitler Appoints Mussert
Dec 10 Adolf Hitler names Anton Mussert "leader of the Dutch people"
Early Report of the Holocaust
Dec 10 An early report of the Holocaust prepared by the Polish government-in-exile, using information obtained by Witold Pilecki, is addressed to UN member states
- Dec 10 North Africa: 5th German panzer army forms under col-gen von Arnim
- Dec 11 Australian Dutch guerrilla troops evacuated to Timor near Australia
- Dec 12 A fire in a hostel in St. John's, Newfoundland, kills 100 people
- Dec 12 German offensive in South Western Stalingrad
- Dec 13 National Football League Championship, Griffith Stadium, Washington, D.C.: Washington Redskins upset Chicago Bears, 14-6
- Dec 13 Seyss-Inquart allows Dutch Nazi Anton Mussert to call himself Leader
- Dec 15 Massachusetts issues 1st US vehicular license plate tabs
- Dec 16 Hitler orders combat against partisans in Russia and the Balkans
- Dec 17 Allies in London sentence German war criminals
- Dec 19 Robert Stroud, convicted murdered, transferred to Alcatraz Federal Penitentiary, where he becomes known as "Birdman of Alcatraz"
- Dec 20 1st Japanese bombing of Calcutta
- Dec 21 US Supreme court declares Nevada separation legal
- Dec 22 World War II: Adolf Hitler signs the order to develop the V-2 rocket as a weapon
- Dec 23 Allies air attack on Den Helder, Netherlands
- Dec 24 First powered flight of V-1 'buzz bomb', Peenemunde, Germany
- Dec 24 Red army occupies German airports at Tasjinskaja & Morozowsk
- Dec 25 Admiral Dalans murderer of Bosinier de la Chapelle, sentenced to death
- Dec 25 British Colonel S W Bailey reaches Mihailovics headquarter
- Dec 25 Soviet artillery and tank battle on German armies at Stalingrad
- Dec 27 1st Japanese women camp (Ambarawa) goes into use
- Dec 27 5th NFL All Star Game, Shribe Park, Philadelphia: NFL All-Stars beat Washington Redskins, 17-14
- Dec 27 The Union of Pioneers of Yugoslavia is founded.
- Dec 28 Oberkommando Wehrmacht orders strategist flight out of Kaukasus
- Dec 28 Robert Sullivan becomes 1st pilot to fly Atlantic 100 times
Sinatramania"
Dec 30 NYC's Times Square greets Frank Sinatra at Paramount Theater, initiating the term "Sinatramania"
- Dec 31 Battle of the Barents Sea between British Navy and German Kriegsmarine off North Cape, Norway