William Weightman Valk (December 12, 1806 in Charleston, South Carolina – September 20, 1879 in Washington, D.C.) was a soldier in the American Civil War and a U.S. Congressman. In 1830, Valk earned a degree in medicine, graduating from the University of South Carolina at Columbia in 1830. He opened a practice in Connecticut. He joined the Navy during the Mexican-American War and became chief surgeon on the USS Constellation. Valk joined the California Gold Rush in 1849 and, upon failure, opened a practice on Long Island. From March 4, 1855 to March 3, 1857, Valk served in New York's 1st District in the United States House of Representatives.