McMillan is an unincorporated community in the town of McMillan, Marathon County, Wisconsin, United States which was at one time an incorporated village. History A post office called McMillan was established in 1881, and remained in operation until it was discontinued in 1919. The community was named for B. F. McMillan, a businessperson in the lumber industry. Notes Unincorporated communities in Marathon County, Wisconsin Unincorporated communities in Wisconsin