Calhoun County is a county in the U.S. state of West Virginia. As of the 2020 census, the population was 6,229, making it the third-least populous county in West Virginia. Its county seat is Grantsville. The county was founded in 1856 and named for South Carolina politician John C. Calhoun.

Grantsville is a town in Calhoun County, West Virginia, United States. The population was 482 at the 2020 census. It is the county seat of Calhoun County. The town was established along the Little Kanawha River in 1865 and named for Ulysses S. Grant. Grantsville is home to Wayne Underwood Park, which includes a .25-mile-long (0.40 km) walking trail, and to the annual West Virginia Wood Festival.