McIntosh County is a county located in the U.S. state of Oklahoma. As of the 2020 census, the population was 18,941. Its county seat is Eufaula. The county is named for an influential Muscogee Creek family, whose members led the migration of the Lower Towns to Indian Territory and served as leaders for generations. It is one of the counties within the jurisdiction of the federally recognized Muscogee Nation; a small portion is within the jurisdiction of the Cherokee Nation of Oklahoma.