Tim Collins, a rookie pitcher with the Kansas City Royals who stands just 5-foot-7. As much as players (and people in general) have gotten taller since the big leagues began, there are few pitchers who have been successful who were so short.
As it turns out, most players who played in the majors from 1876-2009 have been at least 5-foot-10. Of course, there have some notable short players. Freddie Patek was a fine shortstop for the Kansas City Royals despite being just 5-foot-5. And Eddie Gaedel, signed as a stunt by St. Louis Browns' owner Bill Veeck, is the shortest player ever at 3-foot-8.
But perhaps the greatest short player of all is Hack Wilson, a Hall of Fame slugger for the Chicago Cubs, who was the equal of Babe Ruth and Jimmie Foxx for a short time. In fact, Wilson did something no one else has ever done: He drove in more than 190 runs in a season. The year was 1930, a year when batting statistics were off the charts, and Wilson ended the year with 190 RBI and 56 home runs. In 1999, research showed Wilson had driven in 191 runs.
Unfortunately, Wilson had a drinking problem and was never the same player after 1930. Besides his prodigious hitting, Wilson has a claim to fame that no player wants a part of. In Game 4 of the 1929 World Series, he committed two errors on fly balls in one inning. The balls were both lost in the sun and helped the Philadelphia A's to score 10 runs in the 8th inning to erase an 8-0 deficit.
I'm not sure if there are any other Hall of Famers who are as short as Hack Wilson, but none had a more spectacular rise and fall.