Who was the smallest player to ever play professional baseball?

The smallest player to play in the major leagues was 3’7″ Eddie Gaedel. He made his only appearance on April 18, 1951 as part of a promotional stunt by the St. Louis Browns. Wearing the number 1/8, Gaedel was put in to pinch-hit for Frank Saucier in the bottom of the first. The opposing pitcher, Bob Cain, was unable to throw a pitch into Gaedel’s 1½-inch strike zone, and Gaedel walked on four pitches.

Gaedel was paid $100 dollars for his appearance. He was used in several other promotions over the years, but never played in another game.