Ceran St. Vrain, born Ceran de Hault de Lassus de Saint-Vrain (May 5, 1802 – October 28, 1870), was the American son of a French aristocrat who immigrated to the United States in the late 18th century; his mother was from St. Louis, where he was born. To gain the ability to trade, in 1831 he became a naturalized Mexican citizen in what is now the state of New Mexico. He formed a partnership with American traders William, George and Charles Bent; together they established the trading post of Bent's Fort. It was the only privately held fort in the West.