Nicklaus, Jack William, 1940-, American golfer, b. Columbus, Ohio. He began playing golf at the age of 10 and before becoming a professional in late 1961 was considered by many the greatest amateur golfer since Bobby Jones. In his first year as a professional in 1962 he defeated Arnold Palmer in the U.S. Open and won the first World Series of Golf. Capable of hitting drives in excess of 300 yards (270 m), Nicklaus won the Masters six times, the U.S. Open four times, the British Open three times, and the PGA Championship five times.