Frannie is a town in Big Horn and Park counties in the U.S. state of Wyoming. The population was 157 at the 2010 census. In 1894, Frannie's post office opened. Postmaster Morris, the town's first postmaster, had a daughter named Frannie, and the town was named after her. Until 1954, the legal status of Frannie was that of an unincorporated area taking in parts of Big Horn and Park Counties. In 1954, the town was incorporated.