Darlene Ruth Hard (January 6, 1936 – December 2, 2021) was an American professional tennis player, known for her aggressive volleying ability and strong serves. She captured singles titles at the French Championships in 1960 and the U.S. Championships in 1960 and 1961. With eight different partners, she won a total of 13 women's doubles titles and, with another three partners, she won 5 mixed doubles titles in Grand Slam tournaments, and was the finest doubles player of her generation. Her last doubles title, at the age of 33 at the 1969 US Open, came six years after she had retired from serious competition to become a tennis instructor. She also played the US Open singles tournament in 1969, losing in the second round to Françoise Dürr.
According to Lance Tingay, Hard was ranked among the top 10 in the world from 1957 through 1963, reaching a career high of No. 2 in those rankings in 1957, 1960, and 1961. The Miami Herald ranked her No. 1 for the 1961 season. In 1957, she made her first Wimbledon finals appearance, losing to Althea Gibson.
Hard was included in the year-end top-10 rankings issued by the United States Lawn Tennis Association from 1954 through 1963.