The Agile Mangabey is an Old World monkey of the White-eyelid mangabey group found in swampy forests of Central Africa in Equatorial Guinea, Cameroon, Gabon, Central African Republic, Republic of Congo, and DR Congo. Until 1978, it was considered a subspecies of the Tana River Mangabey. More recently, the Golden-bellied Mangabey has been considered a separate species instead of a subspecies of the Agile Mangabey.