Samuel Sullivan "Sunset" Cox (September 30, 1824 – September 10, 1889) was an American Congressman and diplomat. He represented both Ohio and New York in the United States House of Representatives and served as United States Ambassador to the Ottoman Empire. During and before the American Civil War, Cox was a moderate member of the Copperhead faction, who supported peace with the South at any cost. He voted against the Thirteenth Amendment to the United States Constitution. After moving to New York, he focused his advocacy on trade liberalization, civil service reform, and railroad regulation.