Who was the only PGA player to win all four majors in same calendar year?

No man has won a season Grand Slam. Since the Grand Slam of today is different from the one Bobby Jones won, you could argue that he never did it either - but considering his accomplishment, that would just be silly.

Tiger Woods have won all four majors within a period of twelve months, but with a new years eve stuck in the middle.

Two women have won all the LPGA majors of a season: Babe Zaharias who won the three majors held in 1950 and Sandra Haynie who won the only two majors held in 1974.

Bobby Jones' never won a "grand slam" in the modern sense, not just because it didn't exist in his day but for the simple fact that Jones never played professionally. In his day, Golf was still a gentleman's game in the true sense--professional golfers were considered low-class. Jones would have never considered playing for money.