Wetzel County is a county in the U.S. state of West Virginia. As of the 2020 census, the population was 14,442. Its county seat is New Martinsville. The county, founded in 1846, is named for Lewis Wetzel, a famous frontiersman and Indian fighter. Its northern border aligns with the Mason-Dixon line, but is to the west of the line's western terminus.

New Martinsville is a city in and the county seat of Wetzel County, West Virginia, United States, along the Ohio River. The population was 5,186 at the 2020 census.