Seneca is a city in Oconee County, South Carolina, United States. The population was 8,102 at the 2010 census. It is the principal city of the Seneca Micropolitan Statistical Area, an which includes all of Oconee County and which is further included in the greater Greenville-Spartanburg-Anderson, South Carolina Combined Statistical Area.Seneca was named for the nearby Cherokee town of Isunigu, known to the English as "Seneca Town".