Wirt County is a county in the U.S. state of West Virginia. As of the 2020 census, the population was 5,194, making it the least populous county in West Virginia. Its county seat is Elizabeth. The county was created in 1848 by the Virginia General Assembly and named for U.S. Attorney General and presidential candidate William Wirt. The county is served by one high school, Wirt County High School.

William Wirt was an American author and statesman who is credited with turning the position of United States Attorney General into one of influence. He was the longest-serving attorney general in U.S. history. He was also the Anti-Masonic nominee for president in the 1832 election.