John Joseph (Jack) McMahon (December 3 1928 – June 11 1989) was a professional Basketball player and coach. A 6'1" guard from [[St. John's University (New York City)|St. John's University, McMahon was selected by the Rochester Royals in the 1952 NBA Draft. He played 8 seasons in the NBA, for Rochester and the St. Louis Hawks.
He would go on to become a successful coach in the American Basketball League (ABL), the NBA and the ABA, with 11 seasons as a head coach in the three leagues. His first coaching stint was with the Kansas City Steers of the ABL (1961-62 season). The following season he began coaching in the NBA with the Chicago Zephyrs in the 1962-63 season. He would also coach the Cincinnati Royals, the San Diego Rockets, and the ABA's Pittsburgh Condors.