There are others who could easily be added to the Top 20. Some aren't forgotten in this honorable mention category below.
Mike Tyson: 5'9"-5'10", Iron Mike, great heavyweight champion in boxing, until rape charges in 1993 and the ear-biting incident in 1997 made him weird instead of feared.
Kerri Strug: 4'8", member of the famed Magnificent Seven, the gymnastics team that represented USA at the Atlanta Olympics in 1996; nailed the vault, despite a bad ankle, to clinch the gold medal in the team event.
Walter Payton: 5'10","Sweetness," extremely skilled running back for the Chicago Bears, won a Super Bowl in 1985, broke Jim Brown's rushing record and held it for 15 years (16,726 yards).
Eddie Gaedell: 3'7", in one at bat in 1951, he was walked on four straight pitches. Statisticians say that his 1.000 OPS and OBP are to die for!
Calvin Murphy: 5'9", one of the NBA's best free throw shooters.
Allen Iverson: 6', led the NBA in scoring four times, took the Philadelphia 76ers to the 2001 NBA Finals, 2001 NBA MVP, 1997 NBA Rookie of the Year, 11-time NBA All-Star, three-time All-NBA First Team, two-time NBA All-Star Game MVP, 2004 Olympic bronze medalist
Bob Sanders: 5'8", great safety for the Indianapolis Colt (when he's not injured).
Earl Boykins: 5'5", wispy point guard who made strides with the Denver Nuggets recently.
Muggsy Bogues: 5'3", solid PG who had great stats in the NBA's steals, assists, and assist-to-turnover ratio for at least two consecutive years in the NBA in the 1980s and 1990s.
Jimmy Rollins: 5'8", three-time Gold Golve shortshop on three-time NL pennant-winning Philadelphia Phillies, three-time All-Star selection, 2007 NL MVP, 2008 World Series champion.
Steve Tasker: 5'9", four-time AFC champion for the Buffalo Bills in the 1990s.
Don Beebe: 5'11", Buffalo Bill/Green Bay Packer, made Leon Lett look like a fool with "The Play," special teams specialist, Super Bowl XXXI champion.
Desmond Howard: 5'10", phenomenal WR/KR for Michigan, won a Super Bowl with Green Bay during the 1995-96 NFL season.
Martin St. Louis: 5'9", Hart Trophy (MVP) and Art Ross Trophy (most points scored) winner in the 2003-04 season in the NHL for the Tampa Bay Lightning.
Tim Lincecum: 5'11", 2008, 2009 NL Cy Young Award winner, three-time All-Star selection, strikeouts leader in the majors in 2008.
Bart Conner: 5'5", two gold mdeals at the 1984 Olympics (team all-around, parallel bars); Nadia Comaneci's husband.
Sugar Ray Leonard: 5'9", Olympian and boxing middle-weight champion.