- 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 5 Chris Solinsky, American distance runner, born in Stevens Point, Wisconsin
- 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 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 15 Martin Škrtel, Slovakian soccer defender and captain (104 caps; Liverpool FC 242 games), born in Handlová, Slovakia
- 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 25 Alastair Cook, English cricket batsman and captain (161 Tests, 33 x 100s, HS 294, 175 catches; Essex CCC), born in Gloucester, 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 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
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)
Baseball Players
Basketball Stars
Boxers
Footballers
NFL Stars
Tennis Champions