Roberto Alomar Velázquez is a Puerto Rican former second baseman who played in Major League Baseball (MLB) for sixteen seasons, primarily with the Toronto Blue Jays. He is regarded as one of the greatest second basemen and all-around players. During his career, the 12-time All-Star won more Gold Glove Awards (10) than any other second baseman in baseball history, in addition to winning four Silver Slugger Awards for his hitting. Among second basemen, he ranks third in games played (2,320), fifth in stolen bases (474), sixth in plate appearances (10,400), seventh in doubles (504) and assists (6,524), and eighth in hits (2,724), runs (1,508), at-bats (9,073), and double plays turned (1,407). In 2011, Alomar was inducted into the National Baseball Hall of Fame, becoming the first Hall of Fame member to be depicted as a Blue Jays player on his plaque.

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.