Ryan Anthony Klesko (born June 12, 1971 in Westminster, California), is a former Major League Baseball first baseman and corner outfielder, who played for the Atlanta Braves, San Diego Padres, and the San Francisco Giants. He attended Westminster High School in Westminster, California.

Klesko hit at least 21 home runs in eight of his 13 major league seasons, with a high of 34 homers in 1996. His most productive season came in 2001, when he hit .286 with 30 home runs and posted career-highs in RBI (113), runs (105), stolen bases (23) and slugging percentage (.539), and made the National League All-Star team. In 2002, he hit .300 with 29 HR and 95 RBI, and collected career-highs in hits (162) and doubles (39). Defensively he has shuttled around the outfield and first base.

In his career he has a .370 on-base percentage with a .500 slugging average, for a .870 OPS. His .525 slugging percentage as a Brave ranks 4th all-time among the team's career leaders, ahead of Eddie Mathews. His .886 OPS as a Brave ranks him 5th among Braves' all-time leaders.

Klesko became the first player to hit a home run in three consecutive World Series road games when he did so against the Cleveland Indians in Games 3, 4, and 5 of the 1995 World Series. Klesko missed nearly the entire 2006 season due to major shoulder surgery. He returned on September 21, drawing a walk as a pinch-hitter in his first plate appearance. On December 19, 2006, Klesko signed a one-year contract with the San Francisco Giants. Klesko announced his retirement from baseball on April 18, 2008.