Lee Arthur Smith is an American former professional baseball pitcher who played 18 years in Major League Baseball (MLB) for eight teams. Serving mostly as a relief pitcher during his career, he was a dominant closer, was the first pitcher to reach 400 saves, and held the major league record for career saves from 1993 until 2006, when Trevor Hoffman passed his total of 478. He was elected to the National Baseball Hall of Fame as part of the class of 2019 by the Today's Game Era Committee.

In baseball and softball, a relief pitcher or reliever is a pitcher who pitches in the game after the starting pitcher has been removed because of fatigue, ineffectiveness, injury, or ejection, or for other strategic reasons, such as inclement weather delays or pinch hitter substitutions. Relief pitchers are further divided informally into various roles, such as closers, setup men, middle relief pitchers, left/right-handed specialists, and long relievers. Whereas starting pitchers usually throw so many pitches in a single game that they must rest several days before pitching in another, relief pitchers are expected to be more flexible and typically pitch in more games with a shorter time period between pitching appearances but with fewer innings pitched per appearance. A team's staff of relievers is normally referred to metonymically as a team's bullpen, which refers to the area where the relievers sit during games, and where they warm-up prior to entering the game.