Clay County is a county in the U.S. state of Tennessee. As of the 2020 census, the population was 7,581. Its county seat and only incorporated city is Celina. Clay County is named in honor of American statesman Henry Clay, member of the United States Senate from Kentucky and United States Secretary of State in the 19th century.

Celina is a city in and the county seat of Clay County, Tennessee, United States. The population was 1,495 at the 2010 census.