Mbumba Luangu, 'Mbumba of Loango', is the great rainbow serpent of the north-western Kongo peoples, the Vili of the Loango coast and the Yombe of the Mayombe forest. The missionary ethnographer Leo Bittremieux documented the Khimba initiation society, which stood under the protection of this two-headed cosmic serpent whose visible form is the rainbow (Yombe ntshiama or khiama), and he collected carved serpents of Mbumba from the region. Dunja Hersak's field research shows that the Vili and Yombe rely on Mbumba as an ancient nature spirit, an nkisi si or spirit of the land, rather than on ancestor veneration, and Luc de Heusch follows the rainbow python from the Loango coast into the Kongo rites of Haiti, where it endures as the serpent of the petro cult. Mbumba Luangu has no recorded genealogy; it belongs to the class-transcending great spirits of the land and water, individuated by name, cult and myth.