Stefanie Maria Graf ( GRA (H)F, German: [ˈʃtɛfi ˈɡʁaːf] ; born 14 June 1969), known professionally as Steffi Graf and preferring to be called Stefanie since 2001, is a German former professional tennis player. She was ranked as the world No. 1 in women's singles by the Women's Tennis Association (WTA) for a record 377 weeks, and finished as the year-end No. 1 a record eight times. Graf won 107 singles titles on the WTA Tour, including 22 major women's singles titles, the second-most since the start of the Open Era in 1968 and the third-most of all time. She is the only tennis player, male or female, to have won each major singles tournament at least four times — a quadruple career Grand Slam.
A teenage phenomenon, Graf became the youngest player to appear in the main draw of a major at the 1983 French Open aged 13. She improved over the following years and emerged as the player who ended Chris Evert and Martina Navratilova's dominance on women's tennis, winning her first major at the 1987 French Open.