John Drayton Mahaffey Jr. (born May 9, 1948) is an American professional golfer who has won numerous tournaments including 10 PGA Tour events. Mahaffey was born in Kerrville, Texas. He attended the University of Houston in Houston, Texas. He turned pro in 1971 after graduating in 1970 with a degree in psychology. In 1978 he won twice on the tour including one major, the PGA Championship. He also won the World Cup individual and team event where he was paired with Andy North in 1978. Mahaffey played on the 1979 Ryder Cup team.