Red colobuses are Old World monkeys of the subgenus Piliocolobus in genus Procolobus. Some authors elevate Piliocolobus to a full genus, limiting Procolobus to the olive colobus. They are closely related to the black-and-white colobus monkeys (genus Colobus) and some species are often found in groups with the blue monkey. The western red colobus is frequently hunted by the common chimpanzee.

The members of this subgenus are found in western, central and eastern Africa, and the species have largely allo- or parapatric distributions. Most are restricted to humid forests, but the Zanzibar red colobus prefers coastal thickets and scrub. Red colobuses are primarily arboreal and are highly sensitive to hunting and habitat destruction, and have been referred to as probably the most threatened taxonomic group of primates in Africa. If following the taxonomic treatment advocated in Mammal Species of the World, all species except the Central African red colobus are assessed by the IUCN as Endangered or Critically Endangered.