- May 3 Lawrence Tynes, Scottish-American football player, born in Greenock, Scotland
- May 5 Bruno Cheyrou, French footballer, born in Suresnes, France
- May 6 John Abraham, American football player, born in Timmonsville, South Carolina
- May 7 Shawn Marion, American basketball player
- May 8 Cindy Parlow, American soccer midfielder (158 caps; Olympic gold 1996, 2004; silver 2000; FIFA Women's World Cup gold 1999) and executive (President US Soccer 2020-), born in Memphis, Tennessee
- May 8 Lúcio [Lucimar Ferreira da Silva], Brazilian footballer (Inter Milan), born in Planaltina, Brazil
- May 8 Sandra Kleinova, Czech tennis star (1995 Futures-Turku-FIN), born in Prague, Czechoslovakia
- May 9 Aaron Harang, American baseball player
- May 9 Leandro Damián Cufré, Argentine footballer
- May 12 Hossein Reza Zadeh, Iranian weightlifter and politician, born in Ardabil, Iran
- May 12 Josh Phelps, American baseball player, born in Anchorage, Alaska
- May 13 Barry Zito, American baseball player (Oakland Athletics, San Francisco Giants), born in Las Vegas, Nevada
- May 13 Mike Bibby, American basketball player and coach, born in Cherry Hill, New Jersey
- May 14 André Macanga, Angolan footballer
- May 14 Brent Harvey, Australian footballer
- May 14 Eddie House, American basketball player
- May 14 Gustavo Varela, Uruguayan footballer
- May 15 Amy Chow, American gymnast (Olympics-gold/silver, 1996), born in San Jose, California
- May 15 Dwayne DeRosario, Canadian footballer
- May 15 Edu, Brazilian footballer
- May 16 Lionel Scaloni, Argentine soccer wing-back (7 caps; Deportivo La Coruña, Lazio) and manager (Argentina; Copa América 2021), born in Rosario, Argentina
- May 16 Vincent Larusso, American actor (Mighty Ducks; D2; D3), born in Livingston, New Jersey
- May 17 Carlos Peña, Dominican MLB baseball infielder, 2001-14 (Detroit Tigers, Tampa Bay Devil Rays and 6 other teams), and broadcaster, born in Santo Domingo, Dominican Republic
- May 17 Paddy Kenny, Irish goalkeeper
- May 18 Ricardo Carvalho, Portuguese footballer (Chelsea, Real Madrid), born in Amarante, Portugal
- May 19 Marcus Bent, English footballer
- May 21 Jamaal Magloire, Canadian professional basketballer
- May 23 Carolyn Moos, American model and professional basketball player
- May 23 Mike González, American baseball player, born in Corpus Christi, Texas
- May 24 Brad Penny, American baseball pitcher (World Series 2003 Florida Marlins; MLB All Star 2006, 07; NL wins leader 2006 LA Dodgers), born in Blackwell, Oklahoma
- May 24 Johan Holmqvist, Swedish hockey player, born in Tolfta, Sweden
- May 25 Brian Urlacher, American football player (Chicago Bears), born in Pasco, Washington
- May 27 Adin Brown, American soccer player
- May 29 Sébastien Grosjean, French tennis player (Davis Cup 2001; world #4 2002), born in Marseille, France
About May 1978
How Old? 45 years old
Generation: Generation X
Leap Year: No
Baseball Players
Basketball Stars
Boxers
Footballers
NFL Stars
Tennis Champions