This chapter reviews current knowledge of the red colobus, Piliocolobus, a polytypic widespread colobine living in sub-Saharan African forests, woodlands, mangroves, and riparian forests. The taxonomy of Piliocolobus has undergone many changes and is still unresolved, resulting in confusion and possibly hindering conservation efforts. Red colobus is known for being the favourite prey of chimpanzees in many locations, and in several populations red colobus associate with guenons to reduce predation risk. Less well-known are their sexual swellings, which vary greatly in size across the genus, and their graded vocal repertoire that lacks a long call, but in some cases includes female mating calls. Noisy, large multi-female multi-male groups, female dispersal, philopatric males that form coalitions, and lack of female allomothering are considered the norm for the genus but these are not universal. Red colobus is facing extirpation in many locations due to human hunting and forest destruction. Various serious diseases and parasites are also reported for many populations and are often associated with human encroachment into their habitat. Much about the social behaviour is yet to be studied, especially in the less-studied central African species assemblage.