Clancy is an unincorporated community and census-designated place in Jefferson County, Montana, United States. The population was 1,661 at the 2010 census, up from 1,406 in 2000. It is part of the Helena Micropolitan Statistical Area. The town was founded in 1873 as a gold camp and named for prospector William Clancey. A fire in 1902 destroyed many of the buildings in town.