William Pitt Lynde (December 16, 1817-December 18, 1885) was an American lawyer and politician from Wisconsin who served in Congress.
Lynde was born in Sherburne, New York. He graduated from Yale College in 1838 and Harvard Law School in 1841 and was admitted to the bar. He moved to Milwaukee, Wisconsin, shortly thereafter. Lynde became attorney general of the Wisconsin territory in 1844 and U.S. district attorney for Wisconsin in 1845.
When Wisconsin was admitted as a state in 1848, Lynde was elected as a Democrat to the United States House of Representatives, one of Wisconsin's first two representatives. He lost his reelection bid, however; his term lasted from June 5, 1848, to March 3, 1849. He was also an unsuccessful in the 1849 election for associate justice of the Wisconsin Supreme Court.
William Pitt Lynde served as mayor of Milwaukee in 1860. His Wisconsin political career also led him to the state legislature; he served in the Wisconsin State Assembly in 1866 and the State Senate in 1869 and 1870. He returned to the U.S. House of Representatives in 1875, where he served two full terms until 1879, when he retired from politics.
Lynde died in 1885 in Milwaukee at age 68. He is buried at Milwaukee's Forest Home Cemetery.