Kenneth Robert Rosewall (born 2 November 1934) is a former world top-ranking amateur and professional tennis player from Australia. He won a record 23 tennis Majors, including 8 Grand Slam singles titles and, before the Open Era, a record 15 Pro Slam titles; overall, he reached a record 35 Major finals. He won the Pro Grand Slam in 1963. Rosewall won 9 slams in doubles with a career doubles grand slam. He had a renowned backhand and enjoyed a long career at the highest levels from the early 1950s to the early 1970s. Rosewall was world No. 1 player for a number of years in the early 1960s in some rankings. Rosewall was first ranked in the top 20 in 1952 and last ranked in the top 20 in 1977. Rosewall is the only player to have simultaneously held Pro Grand Slam titles on three different surfaces (1962–1963). At the 1971 Australian Open he became the first male player during the open era to win a Grand Slam tournament without dropping a set. Rosewall won world professional championship tours in 1963, 1964, and the WCT titles in 1971 and 1972.
A natural left-hander, he was taught by his father to play right-handed. He developed a powerful and effective backhand but never had anything more than an accurate but relatively soft serve. He was 1.70 m (5 ft 7 in) tall, weighed 67 kg (148 lb) and was ironically nicknamed "Muscles" by his fellow-players because of his lack of them. He was, however, fast, agile, and tireless, with a deadly volley. The father of two and grandfather of five, Rosewall now lives in northern Sydney.
During his long playing career he remained virtually injury-free, something that helped him to still win tournaments at the age of 43 and remain ranked in the top 15 in the world. Although he was a finalist 4 times at Wimbledon, and also at the Wimbledon Pro in 1967, it was the one major tournament that eluded him.
Rosewall was a finalist at the 1974 US Open at 39 years 310 days old, making him the oldest player to participate in two Grand Slam finals in the same year. Before that, in 1972 Rosewall won the Australian Open final at age 37 and 2 months making him the oldest male player to win a Grand Slam singles title.
In the 2012 Tennis Channel series "100 Greatest of All Time" Rosewall was ranked number 13 among all time male tennis players, with only two Australian tennis players ranked ahead of him, Laver and Emerson.