Luis Antonio Castillo is a Dominican former professional baseball second baseman. He played in Major League Baseball for the Florida Marlins, New York Mets, and Minnesota Twins from 1996 through 2010.

In baseball and softball, second baseman, abbreviated 2B, is a fielding position in the infield, between second and first base. The second baseman often possesses quick hands and feet, needs the ability to get rid of the ball quickly, and must be able to make the pivot on a double play. In addition, second basemen are usually right-handed; only four left-handed throwing players have ever played second base in Major League Baseball since 1950. In the numbering system used to record defensive plays, the second baseman is assigned the number 4.