Radnor is an unincorporated community in central Radnor Township, Delaware County, Ohio, United States. Although it is unincorporated, it has a post office, with the ZIP code of 43066. It lies along State Route 203 at its intersection with Radnor Road. The community was named for the Welsh county of Radnorshire. Radnor also has a Memorial Day parade and hog roast every year to support the Radnor Fire Department.