There have been two players who have completed a Calendar Grand Slam in tennis:
Don Budge (1938): American tennis player Don Budge was the first player to achieve a Calendar Grand Slam in men's tennis. In 1938, he won all four major championships in a single calendar year, which at the time consisted of the Australian Championships (now Australian Open), French Championships (now French Open), Wimbledon, and the U.S. National Championships (now US Open).
Rod Laver (1962 and 1969): Australian tennis legend Rod Laver is the only player to achieve the Calendar Grand Slam twice in his career. He accomplished this remarkable feat in 1962 as an amateur and then again in 1969 as a professional player. Laver's Calendar Grand Slams remain an incredible achievement in tennis history.