Cassville is a village in Grant County, Wisconsin, United States. The population was 777 at the 2020 census. The village is located along the Mississippi River, opposite from the mouth of the Turkey River. It is surrounded by the Town of Cassville.

Grant County is the most southwestern county in the U.S. state of Wisconsin. As of the 2020 census, the population was 51,938. Its county seat is Lancaster and its largest city is Platteville. The county is named after the Grant River, in turn named after a fur trader who lived in the area when Wisconsin was a territory. Grant County comprises the Platteville Micropolitan Statistical Area. It is in the tri-state area of Wisconsin, Illinois, and Iowa, and is crossed by travelers commuting to Madison, Wisconsin, from a number of eastern Iowan cities, and by residents of northern Illinois traveling to the Twin Cities or La Crosse, Wisconsin.