The Golden-bellied capuchin (Sapajus xanthosternos) is a capuchin monkey that lives in mangrove and coastal forests in eastern Brazil. Body length is 35–50 cm, weight 1.5–5 kg, and the tail reaches about 50 cm; males are slightly larger. It is diurnal and eats a wide range of foods including fruits, seeds, small animals, insects, and flowers. It lives in multi-male multi-female groups of 8–30 individuals with a dominance hierarchy. Gestation lasts 5–6 months and usually results in a single offspring; ages for weaning and sexual maturity vary among individuals. Population numbers have declined due to habitat loss and hunting, and it is classified as Critically Endangered (IUCN Category I A).