Ovinton J'Anthony "O. J." Mayo (born November 5, 1987 in Huntington, West Virginia), is an American basketball player currently playing with the Memphis Grizzlies of the NBA. He signed with the team on July 8, 2008. He played college basketball for the University of Southern California (USC). As an athlete at Huntington High School and North College Hill High School in Cincinnati, he was considered by several media outlets to be the best high school basketball player in the United States.

He chose to enter the 2008 NBA Draft instead of completing his three remaining years of college eligibility; when he chose Bill Duffy and Associates as his agency, he lost his NCAA eligibility. He was taken third overall by the Minnesota Timberwolves on June 26, 2008. Following the draft, Minnesota traded him and three other players to the Grizzlies in exchange for Kevin Love and three players.

Mayo was a part of the 2008 U.S. Select Team to help get the Olympic team ready for the 2008 Summer Olympics in Beijing.