The mandrill is a primate

Primate

A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

 of the Old World monkey

Old World monkey

The Old World monkeys or Cercopithecidae are a group of primates, falling in the superfamily Cercopithecoidea in the clade Catarrhini. The Old World monkeys are native to Africa and Asia today, inhabiting a range of environments from tropical rain forest to savanna, shrubland and mountainous...

 (Cercopithecidae) family, closely related to the baboon

Baboon

Baboons are African and Arabian Old World monkeys belonging to the genus Papio, part of the subfamily Cercopithecinae. There are five species, which are some of the largest non-hominoid members of the primate order; only the mandrill and the drill are larger...

s and even more closely to the drill

Drill (mammal)

The Drill is a primate of the family Cercopithecidae , closely related to the Baboons and even more closely to the Mandrill.-Description:...

. Both the mandrill and the drill were once classified as baboons in genus Papio

Baboon

Baboons are African and Arabian Old World monkeys belonging to the genus Papio, part of the subfamily Cercopithecinae. There are five species, which are some of the largest non-hominoid members of the primate order; only the mandrill and the drill are larger...

, but recent research has determined they should be separated into their own genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, Mandrillus

Mandrillus

Mandrillus is the genus of the mandrill and its close relative the drill. These two species are closely related to the baboons, and until recently were lumped together as a single species of baboon. Both Mandrillus species have long furrows on either side of their elongated snouts. The adult male...

. The mandrill is the world's largest species of monkey. Charles Darwin

Charles Darwin

Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 wrote, "no other member in the whole class of mammals is coloured in so extraordinary a manner as the adult male mandrills".
The mandrill is perhaps the most colorful primate.