John T. Sebastian, Jr. (November 20, 1921 – April 26, 2003) was an American professional basketball player. He played in numerous leagues, including the National Basketball League. In the NBL, Sebastian played for the Syracuse Nationals, Hammond Calumet Buccaneers, and Detroit Vagabond Kings and averaged 8.0 points per game. At one time he held the Guinness Record for consecutive made free throws made (63).