William Weightman Valk (October 12, 1806 – September 20, 1879) 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.