John Joseph McMahon (December 3, 1928 – June 11, 1989) was a professional basketball player and coach. A 6'1" guard from St. John's University, McMahon was selected by the Rochester Royals in the 1952 NBA draft. He played eight seasons in the National Basketball Association (NBA), for Rochester and the St. Louis Hawks.
McMahon became a successful coach in the American Basketball League, the NBA and the American Basketball Association (ABA), with eleven 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.