The Hungarian excavations carried out in Theban Tomb 400 have recently disclosed the group burial of a Ptolemaic family, whose male members officiated in the service of a lesser-known cult within the domain of Khonsu at Karnak. The cult was centred around the sacred animal avatar of Khonsu called the Baboon or the Living Baboon, who had its own auxiliary sanctuary. As a central element of the cult, the sacred apes kept in the complex were revered as the living incarnations of the baboon-shaped divine avatar. The cult of the Living Baboon functioned as a separate institution and economic unit within the domain of Khonsu: it had its own treasury, administration, and priestly body. The book gives an overview of the history and theological background of the cult and discusses the data pertaining to the priesthood, temple personnel, and mortuary ritualists of Khonsu's sacred apes.