- Dec 1 Yolandi Visser, South African rapper (Die Antwoord), born in Port Albert, South Africa
- Dec 2 Maryna Viazovska, Ukrainian mathematician (Fields Medal 2022, work on densest way to pack spheres in eight dimensions), born in Kyiv, Ukrainian SSR, Soviet Union
- Dec 4 Brooke Adams, American model and professional wrestler, born in St. Louis, Missouri
- Dec 4 Joe Thomas, American College/Pro Football HOF offensive tackle (University of Wisconsin; 10 x Pro Bowl; 6 × First-team All-Pro; Cleveland Browns), born in Brookfield, Wisconsin
- Dec 4 Lauren London, American actress (The Game), born in Los Angeles, California
- Dec 4 Lindsay Felton, American actress (Caitlin's Way), born in Seattle, Washington
- Dec 5 Chris Solinsky, American distance runner, born in Stevens Point, Wisconsin
- Dec 5 Lera Lynn, American singer-songwriter (True Detective), born in Houston, Texas
- Dec 7 Aaron Gray, American NBA basketball player, 2007-14 (Chicago Bulls and 3 other teams), born in Tarzana, California
- Dec 7 Luca Rigoni, Italian footballer, born in Schio, Italy
- Dec 7 Robert Kubica, Polish race car driver (1st Pole to compete in Formula One), born in Kraków, Poland
- Dec 8 Badr Hari, Dutch kickboxer, born in Amsterdam, Netherlands
- Dec 8 Greg Halford, English footballer, born in Chelmsford, United Kingdom
- Dec 8 Sam Hunt, American country pop singer (Take Your Time), born in Cedartown, Georgia
- Dec 10 Jayson Paul, American professional wrestler
- Dec 11 Leighton Baines, English soccer left back (30 caps; Wigan Athletic, Everton 348 games), born in Kirkby, England
- Dec 12 Daniel Agger, Danish footballer, born in Hvidovre, Denmark
- Dec 14 Chris Brunt, Northern Irish footballer, born in Belfast
- Dec 14 Edward Rainsford, Zimbabwean cricketer, born in Kadoma, Zimbabwe
- Dec 14 Jackson Rathbone, American actor (The Twilight Saga), born in Singapore
- Dec 15 Joshua Hayward, British rock guitarist (The Horrors), born in Southend-on-Sea, Essex, England
- Dec 15 Martin Škrtel, Slovakian soccer defender and captain (104 caps; Liverpool FC 242 games), born in Handlová, Slovakia
Theo James (39 years old)
Dec 16 English actor (Divergent, The Time Traveler's Wife), born in High Wycombe, England
Bob Morley (39 years old)
Dec 20 Australian actor (Bellamy Blake-"The 100"; Drew Curtis-"Home and Away"), born in Kyneton, Victoria, Australia
- Dec 20 David Tavaré, Spanish pop-eurodance singer ("Hot Summer Night (Oh La La La)"), born in Pollença, Spain
- Dec 21 Darren Potter, Irish soccer midfielder (5 caps Northern Ireland; Wolverhampton Wanderers, Sheffield Wednesday, Milton Keynes Dons 229 games), born in Liverpool, England
- Dec 22 Basshunter [Jonas Erik Altberg], Swedish record producer and DJ (Now You're Gone), born in Halmstad, Sweden
- Dec 24 Jehnny Beth [Camille Berthomier], French musician, singer-songwriter (John & Jehn; Savages; To Love Is to Live), born in Poitiers, France
- Dec 25 Alastair Cook, English cricket batsman and captain (161 Tests, 33 x 100s, HS 294, 175 catches; Essex CCC), born in Gloucester, England
- Dec 25 Georgia Moffett, British actress, born in London
- Dec 25 Jessica Origliasso, Australian singer-songwriter and actress (The Veronicas), born in Albany Creek, Queensland, Australia
- Dec 25 Lisa Origliasso, Australian singer-songwriter and actress (The Veronicas), born in Albany Creek, Queensland, Australia
- Dec 25 Nadiya Hussain, English TV chef and writer (Nadiya's British Food Adventure), born in Luton, England
- Dec 26 Alex Schwazer, Italian race walker, born in Sterzing, Italy
- Dec 27 Gilles Simon, French tennis player (world #6 2009; Davis Cup 2017), born in Boulogne-Billancourt, France
- Dec 27 Pleasure P. [Marcus Cooper], American R&B singer (Pretty Ricky), born in Miami, Florida
- Dec 28 Alex Lloyd, British racing driver, born in Manchester, United Kingdom
- Dec 28 Beverly Mullins, American wrestler & model, born in Clearwater, Florida
- Dec 28 Leroy Lita, Congolese football player, born in Kinshasa, Democratic Republic of the Congo
- Dec 28 Martin Kaymer, German golfer (PGA C'ship 2010, US Open 2014), born in Düsseldorf, Germany
- Dec 30 Andra Day [Cassandra Batie], American singer-songwriter ("Rise Up"), and actress (The United States vs. Billie Holiday), born in Edmonds, Washington
- Dec 30 Dalia Stasevska, Ukrainian-Finnish conductor (Lahti Symphony, 2021-present), born in Kyiv, Ukrainian SSR, USSR (now Ukraine)
LeBron James (39 years old)
Dec 30 American basketball forward (NBA C'ship & MVP 2012, 2013, 2016, 2020; 16 × NBA All-Star; Olympic gold 2008, 12; Cleveland Cavaliers, Miami Heat, LA Lakers), born in Akron, Ohio
- Dec 30 Randall Azofeifa, Costa Rican footballer
About December 1984
How Old? 39 years old
Generation: Millennial
Leap Year: Yes
Chinese Zodiac: Rat
Star Signs: Sagittarius (Nov 22 - Dec 21), Capricorn (Dec 22 - Jan 19)
Greatest Generation
Silent Generation
Baby Boomer
Generation X
Millennial
Generation Z