A phantom ballplayer is either a baseball player who is incorrectly listed in source materials as playing in a Major League Baseball (MLB) game, often the result of typographical or clerical errors, or a player who spent time on an MLB active roster without ever appearing in an MLB contest during his career. Most of the first form of phantom players date from the 19th or early 20th century, with at least one showing up as late as World War II.
A modern-day phantom ballplayer is generally caused by the player being removed from the active roster by a subsequent action (such as being optioned to a minor league team) or the team reaching the end of their season, and the player not having later opportunity to play in a major league game. Many of these phantom players were September call-ups in backup roles.