Monroe County is a county located on the eastern border of the U.S. state of Ohio, across the Ohio River from West Virginia. As of the 2020 census, the population was 13,385, making it the second-least populous county in Ohio. Its county seat is Woodsfield. The county was created in 1813 and later organized in 1815.

Woodsfield is a village and the county seat of Monroe County, Ohio, United States, located about 30 miles (48 km) northeast of Marietta. The population was 2,210 at the 2020 census.