The red-tailed monkey (Cercopithecus ascanius), also known as the black-cheeked white-nosed monkey, red-tailed guenon, redtail monkey, or Schmidt's guenon, is a species of primate in the family Cercopithecidae.

It is found in Angola, Cameroon, Central African Republic, Democratic Republic of the Congo, Kenya, Rwanda, South Sudan, Tanzania, Uganda, Zambia, and possibly Burundi. The red-tailed monkey is usually black, red, or orange. Although native to this region, it has spread north and south as well as it can survive in different habitats and under different conditions. It is a distinct creature in its habitats and is gradually becoming endangered due to deforestation and over-exploitation through hunting and predation.:missing::missing: