Nicholas Boilvin (1761–1827) was a 19th-century American frontiersman, fur trader, and U.S. Indian Agent. He was the first appointed agent to the Winnebagos, as well as the Sauk and Fox, and one of the earliest pioneers to settle in present-day Prairie du Chien, Wisconsin. His sons and both became successful businessmen in Wisconsin during the mid- to late 19th century. His wife was formerly a Miss St. Cyr of St. Louis. (WHC v.10, p. 222)