William Best Hesseltine (February 21, 1902 - December 8, 1963) was an American historian and politician who became the Socialist Party candidate for U.S. President in 1948. As a historian and professor at the University of Wisconsin–Madison for nearly three decades, Hesseltine's field of expertise was mid-19th century American history, especially the Civil War, Reconstruction Era and American South. He also became known as the mentor of a generation of American historians, many of whom also won prizes for their writing.