The tufted capuchin (Sapajus apella), also known as brown capuchin, black-capped capuchin, or pin monkey, is a New World primate from South America and the Caribbean islands of Trinidad and Margarita. As traditionally defined, it is one of the most widespread primates in the Neotropics, but it has recently been recommended considering the black-striped, black and golden-bellied capuchins as separate species in a new genus, thereby effectively limiting the tufted capuchin to the Amazon basin and nearby regions. However, the large-headed capuchin (S. a. macrocephalus), previously defined as a distinct species, has been reclassified as a subspecies of the tufted capuchin, expanding its range east to Peru and Ecuador and south to Bolivia.

The tufted capuchin is an omnivorous animal, mostly feeding on fruits and invertebrates, although it sometimes feeds on small vertebrates (e.g. lizards and bird chicks) and other plant parts. It can be found in many different kinds of environment, including moist tropical and subtropical forest, dry forest, and disturbed or secondary forest.

Like other capuchins, it is a social animal, forming groups of 8 to 15 individuals that are led by an alpha or dominant male.

At one point all tufted capuchins were classified as Cebus apella. Under such taxonomy, the range of C. apella would extend throughout much of South America from Colombia to northern Argentina. Although she did not describe specific or subspecific nomenclature, Torres de Assumpção (1983; 1988) described differences between tufted capuchins from five distinct geographic regions of Brazil and high phenotypic variation of individuals in a sixth area that had a greater selection pressure. In 2001, Silva Júnior proposed that the robust capuchins such (formerly the C. apella group) be placed in a separate genus, Sapajus, from the gracile capuchins (formerly the C. capucinus group) which retain the genus Cebus. This was supported by Jessica Lynch Alfaro et al. in 2011. Groves (2005) recognized six subspecies: Cebus apella apella, C. a. fatuellus, C. a. macrocephalus, C. a. margaritae, C. a. peruanus, C. a. tocantinus. The IUCN follows Silva (2001) and recognise the species as monotypic, though the subspecies status of S. a. margaritae is unclear.

The tufted capuchin is more powerfully built than the other capuchins, with rougher fur and a long, thick tail. It has a bundle of long, hardened hair on the forehead that can be raised as a sort of "wig". The fur is brownish gray, with the belly being somewhat lighter-colored than the rest of the body. The hands and feet are black. The tail is prehensile: strong and can be used for grasping, as an extra limb.

The tufted capuchin has a head-body length of 32 to 57 centimetres (13 to 22 in), a tail length of 38 to 56 centimetres (15 to 22 in), and a weight of 1.9 to 4.8 kilograms (4.2 to 10.6 lb), with the males generally being larger and heavier than the females.

The tufted capuchin is a diurnal, arboreal primate species, but it often forages on the ground and walks longer distances between trees that are too far apart to jump.

The tufted capuchin lives in groups of two to twenty or more animals. A single group usually contains at least one adult male, with some groups having multiple males. Where multiple males are present, one of the males is dominant. He accepts only a few monkeys in his direct surroundings, mainly younger animals and a few females. The dominant male and the group members that are close to him have the privilege to eat first in case of food scarcity, while subordinate monkeys have to wait until they are ready.