Mongo, any of several peoples living in the African equatorial forest, south of the main Congo River bend and north of the Kasai and Sankuru rivers in Congo (Kinshasa). They include such ethnic groups as the Bokote, Ekonda, Bolia, Sengele, Ntomba, Ndengese, Songomeno, Mbole, Bongandu, Boyela, Nkutu, and Tetela-Kusu. They speak dialects of a common language, Mongo or Nkundo, a member of the Benue-Congo branch of the Niger-Congo languages. Many groups are disappearing because of falling birth rate.

The Mongo traditionally cultivated cassava and bananas but also relied on wild-plant gathering, fishing, and hunting. Their material culture was generally simple, though some hunting and fishing techniques were well developed. Descent was patrilineal, and communities were grouped in lineages stemming from a single ancestor. Lineage elders were invested with authority that derived partly from religious sources. Because there was no organization other than the lineage, feuds, covenants between lineages, and marriage payments were means of solving issues that arose between lineages. Only among some southern groups did there exist a true chieftainship, based upon divine right.

Mongo religion placed strong emphasis on ancestor worship and on beliefs in nature spirits responsible for fertility, as well as on magic, sorcery, and witchcraft. Witch-finding cults were prominent, and divination played an important role in them. Mongo art was mainly oral, and their talking-drum literature and songs showed a rich artistic content.