Platyrrhini is a parvorder of primates. Members of this parvorder are called platyrrhines, or New World monkeys, and include marmosets, tamarins, and capuchin, squirrel, night, titi, saki, howler, spider, and woolly monkeys. Platyrrhini is one of three clades that form the suborder Haplorrhini, itself one of two suborders in the order Primates. They are found in South and Central America in forests and savannas. They range in size from the western pygmy marmoset, at 12 cm (5 in) plus a 17 cm (7 in) tail, to some species of howler monkey in the genus Alouatta, at 92 cm (36 in) plus a 92 cm (36 in) tail. Platyrrhines primarily eat fruit, leaves, and insects. Most platyrrhines do not have population estimates, but the ones that do range from 250 mature individuals to 10,000. Twenty-one species are categorized as endangered, and a further fourteen species are categorized as critically endangered.

The 160 extant species of Platyrrhini are divided into five families. Aotidae contains eleven night monkey species in a single genus. Atelidae contains twenty-three species divided between one genus in the howler monkey subfamily Alouattinae and three genera in the spider monkey and wooly monkey subfamily Atelinae. Callitrichidae contains 53 species of tamarins and marmosets in seven genera. Cebidae contains eighteen species divided between two genera in the capuchin subfamily Cebinae and one genus in the squirrel monkey subfamily Saimiriinae. Pitheciidae contains 54 species divided between three genera in the titi monkey subfamily Callicebinae and three genera in the uakari and saki monkey subfamily Pitheciinae. Dozens of extinct prehistoric platyrrhine species have been discovered, though due to ongoing research and discoveries the exact number and categorization is not fixed.^[1]

Conservation status codes listed follow the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Range maps are provided wherever possible; if a range map is not available, a description of the platyrrhine's range is provided. Ranges are based on the IUCN Red List for that species unless otherwise noted.

The parvorder Platyrrhini consists of five extant families: Aotidae, Atelidae, Callitrichidae, Cebidae, and Pitheciidae. Aotidae contains eleven species in one genus. Atelidae is divided into two subfamilies: Alouattinae, containing twelve species in one genus, and Atelinae, containing eleven species in three genera. Callitrichidae contains 53 species in seven genera. Cebidae is divided into two subfamilies: Cebinae, containing eleven species in two genera, and Saimiriinae, containing one genus of seven species. Pitheciidae is divided into two subfamilies: Callicebinae, containing 32 species in three genera, and Pitheciinae, containing 22 species in three genera.

The following classification is based on the taxonomy described by the reference work Mammal Species of the World (2005), with augmentation by generally accepted proposals made since using molecular phylogenetic analysis, as supported by both the IUCN and the American Society of Mammalogists.^[3]