Left-handed specialist

In baseball, a left-handed specialist (also known as lefty specialist) is a relief pitcher who throws left-handed and specializes in pitching to left-handed batters, weak right-handed batters, and switch-hitters who bat poorly right-handed. Because baseball practices permanent substitution, these pitchers frequently pitch to a very small number of batters in any given game, and rarely pitch to strictly right-handed batters. Most Major League Baseball (MLB) teams have several left-handed pitchers on their rosters, at least one of whom is a left-handed specialist.

Prior to 2020, when the MLB rules were amended to require all pitchers to complete an inning or face at least three hitters, some left-handed specialists commonly faced only one batter before leaving the game. Such a specialist was sometimes called a LOOGY (or Lefty One-Out GuY), coined by John Sickels, sometimes used pejoratively.