Bobby Jones has achieved the feat of winning the grand slam.
He did so as an amateur, before the present-day tournament requirements were instituted.
He won the British Amateur tournament in Scotland on May 31, 1930. Next, on June 20, 1930, he won the British Open in Holyoke, England, with a four-round total of 291. On July 12, he won the U.S. Open in Minneapolis, Minnesota, with a four-round total of 287. Finally, on September 27, in Ardmore, Pennsylvania, he won the U.S. Amateur championship.
Despite this accomplishment, Bobby Jones never became a professional golfer.
Since World War II, the grand slam has consisted of the U.S. Open, the Masters, the British Open, and the PGA Championship.