- Jan 1 Alok Kapali, Bangladeshi cricket all-rounder (17 Tests; 69 ODIs), born in Sylhet, Bangladesh
- Jan 1 Paolo Guerrero, Peruvian soccer striker (102 caps; Hamburger SV, Internacional), born in Lima, Peru
- Jan 2 Colleen Taylor, American journalist
- Jan 5 Amanda Hearst, American heiress, born in NYC, New York
- Jan 6 A. J. Hawk, American football player, born in Kettering, Ohio
- Jan 6 Kate McKinnon, American actress and comedian (Ghostbusters), born in Sea Cliff, New York
- Jan 6 Sean O'Brien, Australian professional windsurfer, born in Carlow, Republic of Ireland
- Jan 7 Jon Lester, American baseball player, born in Tacoma, Washington
- Jan 8 Jeff Francoeur, American baseball player, born in Atlanta, Georgia
- Jan 10 Karen Souza, Argentinian jazz and bossa nova singer, songwriter, and producer (Essentials; Velvet Vault), born in La Pampa, Argentina
- Jan 12 Scott Olsen, American baseball player, born in Kalamazoo, Michigan
- Jan 14 Mike Pelfrey, American baseball player, born in Wright-Patterson Air Force Base, Ohio
- Jan 15 Megan Jendrick, American swimmer, born in Tacoma, Washington
- Jan 15 Victor Rasuk, American actor, born in NYC, New York
- Jan 16 Jared Slingerland, Canadian rock guitarist and electronic musician, born in Kelowna, British Columbia
- Jan 17 Calvin Harris, Scottish DJ, singer-songwriter and producer ("We Found Love"), born in Dumfries, Scotland
- Jan 18 Benji Schwimmer, American dancer and choreographer (So You Think You Can Dance), born in Newport Beach, California
- Jan 18 Kristy Lee Cook, American country singer (American Idol, season 7), born in Seattle, Washington
- Jan 18 Michael Kearney, American child prodigy, born in Honolulu, Hawaii
- Jan 18 Seung-Hui Cho, South Korean-born spree killer (Virginia Tech), born in Onyang-dong, South Korea (d. 2007)
- Jan 19 Euan Blair, eldest son of British Prime Minister Tony Blair, born in London, United Kingdom
- Jan 19 Karun Chandhok, Indian racing driver, born in Chennai, India
- Jan 19 Thomas Vanek, Austrian ice hockey player, born in Baden bei Wien, Austria
- Jan 20 Olivia Hallinan, English actress, born in Hounslow, United Kingdom
- Jan 20 Toni Gonzaga, Filipino singer and actress, born in Rizal, Philippines
- Jan 21 Hiroki Yuhara, Japanese rugby union hooker (22 caps; Toshiba Brave Lupus), born in Chiba, Japan (d. 2020)
- Jan 21 Luke Grimes, American actor (Yellowstone), born in Dayton, Ohio
- Jan 22 Ben Eager, Canadian NHL ice hockey player, 2004-15 (Philadelphia Flyers, Chicago Black HAwks, and 3 other teams), born in Ottawa, Ontario
- Jan 22 Leon Powe, American basketball player, born in Oakland, California
- Jan 22 Maceo Rigters, Dutch footballer, born in Amsterdam, Netherlands
- Jan 22 Raica Oliveira, Brazilian supermodel, born in Rio de Janeiro, Brazil
- Jan 23 Arjen Robben, Dutch football player, born in Bedum, Netherlands
- Jan 24 Scott Kazmir, American baseball player, born in Houston, Texas
- Jan 24 Witold Kiełtyka, Polish drummer (Decapitated), born in Krosno, Poland (d. 2007)
- Jan 25 Robinho [Robson de Souza], Brazilian soccer forward (100 caps; Santos), born in São Vicente, Brazil
- Jan 26 Layla Kayleigh, British television personality, born in London, United Kingdom
- Jan 26 Luo Xuejuan, Chinese swimmer (Olympic gold women's 100m breaststroke 2004; World C'ship gold x 5), born in Hangzhou, China
- Jan 27 Davetta Sherwood, American actress (The Young And The Restless, 2006 - "Lily"), born in Mount Vernon, New York
- Jan 28 Andre Iguodala, American NBA basketball player, 2004-present (Philadelphia 76ers, golden State Warriors, and 2 other teams), born in Springfield, Illinois
- Jan 30 Jeremy Hermida, American baseball player, born in Atlanta, Georgia
- Jan 30 Kid Cudi [Scott Mescudi], American rapper (Man on the Moon: The End of Day), born in Cleveland, Ohio
- Jan 31 Jeremy Wariner, American 400m runner, born in Irving, Texas
- Jan 31 Vernon Davis, American football tight end, born in Washington, D.C.
About January 1984
How Old? 39 years old
Generation: Millennial
Leap Year: Yes