The Sanje mangabey (Cercocebus sanjei) is a highly endangered Old World monkey of the white-eyelid mangabey group from Tanzania. They are about 50-65 centimeters long, excluding tail, and weigh about 7-9 kilograms, and their body color is greyish. They live in valley forests, but are mostly ground-dwelling, which makes them susceptible to hunting and poaching. Fruit makes up about 70% of their diet, while foliage makes up most of the rest.