Greene County is located in the southwestern portion of Ohio. As of the 2020 census, the population was 167,966. Its county seat is Xenia and its largest city is Beavercreek. The county was established on March 24, 1803 and named for General Nathanael Greene, an officer in the Revolutionary War. Greene County is part of the Dayton, OH Metropolitan Statistical Area.

Xenia is a city in and the county seat of Greene County, Ohio, United States. Located in southwestern Ohio, it is 15 miles (24 km) east of Dayton and is part of the Dayton metropolitan area as well as the Miami Valley region. As of the 2020 census, the city had a population of 25,441. The city's name comes from the Greek word Xenia (ξενία), which means "hospitality".