William Augustus Larned was an American tennis player who was active at the beginning of the 20th century. He won seven singles titles at the U.S. National Championships.

The US Open Tennis Championships, commonly called the US Open, is a hardcourt tennis tournament held annually in Queens, New York. Since 1987, the US Open has been chronologically the fourth and final Grand Slam tournament of the year. The other three, in chronological order, are the Australian Open, French Open and Wimbledon. The US Open starts on the last Monday of August and continues for two weeks, with the middle weekend coinciding with the US Labor Day holiday. The tournament is one of the oldest tennis championships in the world, originally known as the U.S. National Championship, for which men's singles and men's doubles were first played in August 1881. It is the only Grand Slam that was not affected by cancellation due to World War I and World War II, nor interrupted by the COVID-19 pandemic in 2020. All the players participating should be at least fourteen (14) years old.