Stephen Duncan (March 4, 1787 – January 29, 1867) was an American planter and banker in Mississippi during the Antebellum South. He was born and studied medicine in Pennsylvania, but moved to Natchez District, Mississippi Territory in 1808 and became the wealthiest cotton planter and the second-largest slave owner in the United States with over 2,200 slaves. He owned 15 cotton and sugar plantations, served as President of the Bank of Mississippi, and held major investments in railroads and lumber.