Greeneville is a town in and the county seat of Greene County, Tennessee, United States. The population as of the 2020 census was 15,479. The town was named in honor of Revolutionary War hero Nathanael Greene, and it is the second oldest town in Tennessee. It is the only town with this spelling in the United States, although there are numerous U.S. towns named Greenville. The town was the capital of the short-lived State of Franklin in the 18th-century history of East Tennessee.