The guenons are the genus Cercopithecus of Old World monkeys. Not all the members of this genus have the word "guenon" in their common names, and because of changes in scientific classification, some monkeys in other genera may have common names that do include the word "guenon". Nonetheless the use of the term guenon for monkeys of this genus is widely accepted.
All members of the genus are endemic to Sub-Saharan Africa, and most are forest monkeys. Many of the species are quite local in their ranges, and some have even more local subspecies. Many are threatened or endangered because of habitat loss.
The species currently placed in the genus Chlorocebus, known as vervet monkeys or green monkeys, were formerly considered as a species in this genus, Cercopithecus aethiops.