Stefanie Maria ("Steffi") Graf (born June 14, 1969 in Mannheim, Germany) is a former World No. 1 woman tennis player from Germany. She is widely considered one of the greatest, if not the greatest, female tennis player in history. Graf won 22 Grand Slam singles titles. In 1988, she became the only player to achieve the "Golden Slam" – capturing all four Grand Slam titles and the Olympic Gold Medal in the same year. She was ranked the Women's Tennis Association's No. 1 player for a record 377 weeks (the longest of any player, male or female, since rankings began) and is the only player, male or female, to have won all four Grand Slam tournaments (Wimbledon, the US Open, the French Open and the Australian Open) at least four times each.

A notable feature of Graf's game was her versatility across all playing surfaces, exemplified by her winning 6 French Open singles titles (second to Chris Evert, a strong clay court player) and 7 Wimbledon singles titles (third behind Martina Navratilova and Helen Wills Moody, strong grass court players). None of her rivals for the title of "greatest female tennis player in history" can make this claim. Navratilova was comparatively weak on clay, won only 18 Grand Slam singles titles, and never achieved the calendar year "Grand Slam" in singles. Margaret Court, the only player to have won more Grand Slam singles titles than Graf, won 11 of her 24 titles at the Australian Open when many of the world's top players routinely skipped the event. Evert was comparatively weak on grass. Monica Seles has never won the Wimbledon singles title. Billie Jean King, Suzanne Lenglen, and Wills-Moody won fewer major tournaments.