George Kenneth "Ken" Griffey, Jr. (born November 21, 1969), nicknamed "Junior" and "The Kid", is an American former professional baseball outfielder who played 22 years in Major League Baseball (MLB) for three teams, from 1989–2010. He spent most of his career with the Seattle Mariners and Cincinnati Reds, along with a short stint with the Chicago White Sox. A 13-time All-Star, Griffey was one of the most prolific home run hitters in baseball history; his 630 home runs rank as the sixth-most in MLB history. Griffey was also an exceptional defender and won 10 Gold Glove Awards in center field. He is tied for the record of most consecutive games with a home run (8 games, with Don Mattingly and Dale Long).

Although popular with fans around the league, Griffey was unable to shake reports of his petulant demeanor throughout his major league baseball career. Griffey signed lucrative deals with companies of international prominence like Nike and Nintendo (owners of the Mariners); his popularity reflected well upon MLB and is credited by some with helping restore its image after the 1994 labor dispute. Griffey is one of only 29 players in baseball history to date to have appeared in Major League games in four different calendar decades.