Maureen Catherine ("Little Mo") Connolly (born September 17, 1934 - died June 21, 1969) was an American tennis player who was the first woman to win all four Grand Slam tournaments during the same calendar year.

Connolly was born in San Diego, California, United States. As a child, she loved horseback riding, but her mother was unable to pay the cost of riding lessons. So, she took up the game of tennis.

Connolly's career began at the age of 10 on the municipal courts of San Diego. Her first coach, Wilbur Folsom, encouraged her to switch from a left-handed grip to right and she soon became a baseline specialist with tremendous power, accuracy, and an especially strong backhand. Aged 14, she won 56 consecutive matches and the following year became the youngest ever to win the U.S. national championship for girls 18 and under.

At the 1951 U.S. Championships, the 16 year old Connolly defeated Shirley Fry to become, at that time, the youngest ever to win America's most prestigious tennis tournament.

Connolly successfully defended her U.S. title and won Wimbledon in 1952. For the 1953 season, she hired a new coach, the Australian Davis Cup captain Harry Hopman, and entered all four Grand Slam tournaments for the first time. She defeated Julie Sampson Haywood in the Australian Championships final and Doris Hart in the finals of the French Championships, Wimbledon, and the U.S. Championships to become the first woman, and only the second person, to win the world's four major titles in the same year, commonly known as a "Grand Slam." She lost only one set in those four tournaments.

In 1954, Connolly did not defend her title at the Australian Championships but successfully defended her French and Wimbledon championships. On July 20, 1954, just two weeks after she won her third straight Wimbledon title, she was horseback riding when an accident with a truck crushed her right leg, ending her tennis career at age 19.

Grand Slam singles results for Connolly's 11 appearances:

#Australian Championships - 1 time: Winner 1953

#French Championships - 2 times: Winner 1953, 1954

#Wimbledon - 3 times: Winner 1952, 1953, 1954

#U.S. Championships - 5 times (1949-1953): Winner 1951, 1952, 1953

Connolly won the last nine Grand Slam singles tournaments she played, including 50 consecutive singles matches.

During her Wightman Cup career from 1951 through 1954, Connolly won all seven of her singles matches.

Connolly's achievements made her the darling of the media and one of the most popular p...