December 1st
- Aids Awareness Day (World)
- Antarctica Day
- Basketball Day
- Bifocals at the Monitor Liberation Day
- Civil Air Patrol Day
- Clark Kent’s (Superman) Birthday
- Day With(out) Art Day
- Eat a Red Apple Day
- Rosa Parks Day
December 2nd
- Abolition of Slavery Day (International)
- Cider Monday ~ Monday after Thanksgiving
- Cyber Monday ~ Monday after Thanksgiving
- Fritters Day
- Mutt Day
- Safety Razor Day
- Special Education Day
December 3rd
- Advent Begins ~ Date Varies
- Giving Tuesday ~ Day after Cyber Monday
- Persons with Disabilities Day (International)
- Roof Over Your Head Day
- Trick Shot Day (World) ~ First Tuesday of December
December 4th
- Cookie Day
- Dice Day
- Package Protection Day ~ Wednesday after Thanksgiving
- Santa’s List Day
- Special Trick Shot Day
- Sock Day
- Special Kid’s Day ~ First Wednesday of December
- Wear Brown Shoes Day
- Wildlife Conservation Day (World)
December 5th
- Bathtub Party Day
- Columbian International Day of the Reef
- Ninja Day (International)
- Repeal Day
- Sachertorte Day
- Soil Day (World)
- Volunteer Day for Economic & Social Development (International)
December 6th
- Bartender Appreciation Day ~ First Friday of December
- Faux Fur Friday ~ First Friday of December
- Miner’s Day
- Mitten Tree Day
- Pawnbroker’s Day
- Put on Your Own Shoes Day
- St. Nicholas Day
December 7th
- Chester Greenwood Day ~ First Saturday of December
- Civil Aviation Day (International)
- Cotton Candy Day
- Earmuff Day ~ First Saturday of December
- Letter Writing Day
- Pear Day (World)
- Pearl Harbor (Remembrance) Day
- Rhubarb Vodka Day ~ First Saturday of December
- Skywarn Recognition Day ~ First Saturday of December
December 8th
- Bodhi Day (Traditional)
- Brownie Day
- Candle Lighting Day (Worldwide) ~ Second Sunday in December
- Children’s Day (International) ~ Second Sunday in December
- Choral Day (World) ~ Second Sunday in December
- Lard Day
- Pretend to be a Time Traveler Day
- Take it in the Ear Day
December 9th
- Anti-Corruption Day (International)
- Christmas Card Day
- Cremation Day
- Day of Commemoration and Dignity of the Victims of the Crime of Genocide and the Prevention of this Crime (International)
- Green Monday ~ Second Monday in December
- Pastry Day
- Weary Willie Day
December 10th
- Animal rights Day (International)
- Dewey Decimal System Day
- Human Rights Day
- Jane Addams Day
- Nobel Prize Day
December 11th
- App Day
- Kaleidoscope Day
- Magnum P.I. Day
- Mountain Day (International)
- Noodle Ring Day
- UNICEF Birthday
December 12th
- 12-Hour Fresh Breath Day
- Cocoa Day
- Ding-a-Ling Day
- Gingerbread House Day
- Lost Day
- National Guard Birthday
- Neutrality Day (International)
- Our Lady of Guadalupe Day
- Poinsettia Day
December 13th
- Horse Day
- Ice Cream Day
- Salesperson Day ~ Second Friday of December
- Official Lost & Found Day ~ Second Friday of December
- Pick a Pathologist Day
- Violin Day
December 14th
- Bouillabaisse Day
- Gingerbread Decorating Day ~ Second Saturday of December
- Monkey Day (International)
- Roast Chestnuts Day
- Shareware Day ~ Second Saturday of December
- Yoga Day
December 15th
- Bill of Rights Day
- Cat Herders Day
- Cupcake Day
- Lemon Cupcake Day
- Tea Day (International)
- Wear Your Pearls Day
- Zamenhof Day (Esperanto Literature Day)
December 16th
- Barbie and Barney Backlash Day
- Chocolate Covered Anything Day
- Zionism Day
December 17th
- A Christmas Carol Day
- Answer the Telephone Like Buddy the Elf Day
- Clean Air Day
- Maple Syrup Day
- Wright Brothers Day
December 18th
- Arabic Language Day
- Bake Cookies Day
- Give a Wine Club Day
- Migrants Day (International)
- Roast Suckling Pig Day
December 19th
- Free Shipping Day (Participating Retailers) ~ Third Thursday of December
- Look for an Evergreen Day
- Oatmeal Muffin Day
- Re-Gifting Day ~ Third Thursday of December
December 20th
- Games Day
- Go Caroling Day
- Human Solidarity Day (International)
- Mudd Day
- Poet Laureate Day
- Prayer and Action for Children Day (World)
- Sangria Day
- Ugly Sweater Day ~ Friday of Third Full Week of December
- Underdog Day ~ Third Friday of December
December 21st
- Ann & Samantha Day ~ Summer & Winter Solstices
- Celebrate Short Fiction Day ~ Winter Solstice
- Crossword Puzzle Day
- Dalek Remembrance Day (International)
- Flashlight Day (Shortest Day of the Year) ~ Winter Solstice
- Forefather’s Day
- Global Orgasm Day ~ Summer & Winter Solstices
- Homeless Person’ Remembrance Day
- Humbug Day
- Look on the Bright Side Day
- Phileas Fogg Win a Wager Day
- Short Girl Appreciation Day (Shortest Day of the Year) ~ Winter Solstice
- Winter Begins ~ Winter Solstice
- World Peace Day ~ Winter Solstice
- Wreaths Across America Day ~ Third Saturday of December
- Yalda
- Yule
December 22nd
- Be a Lover of Silence Day
- Chanukah Begins ~ Date Varies
- Date Nut Bread Day
- Hanukah ~ Date Varies
- Winter Solstice ~ Date Varies
- Yule
December 23rd
- Festivus
- Human Light Celebration
- Metric Conversion Day
- Roots Day
December 24th
- Chocolate Day
- Christmas Eve
- Egg Nog Day
December 25th
- A’Phabet Day (No “L” Day)
- Christmas
- Christmas Pudding Day
- Pumpkin Pie Day
December 26th
- Boxing Day
- Candy Cane Day
- Kwanzaa Begins
- Thank You Note Day
- Whiner’s Day
December 27th
- Free Balloon Day
- Fruitcake Day
- Howdy Doody Day
- Make Cutout Snowflakes Day
- Visit the Zoo Day
December 28th
- Card Playing Day
- Chocolate Candy Day
- Endangered Species Act Day
- Holy Innocents Day
- Pledge of Allegiance Day
December 29th
- Pepper Pot Day
- Tick Tock Day
- YMCA Day
December 30th
- Bacon Day
- Bicarbonate of Soda Day
- Falling Needles Family Fest Day
December 31st
- First Nights
- Champagne Day
- Leap Second Time Adjustment Day
- Look on the Bright Side Day
- Make Up Your Mind Day
- New Year’s Eve
- New Year’s Eve Banished Words List Day
- New Year’s Dishonor List Day
- No Interruptions Day ~ Last Business Day of the Year
- Universal Hour of Peace Day
- World Healing Day
- World Peace Meditation Day