Which African monkey has a bright blue face and red nose?

The mandrill is the African monkey known for a bright blue face and red nose.

Mandrills are large Old World monkeys native to rainforest and forest-edge habitats in parts of Central Africa. Adult males have especially vivid facial coloration: blue ridges run along the muzzle, while the nose and lips can be red. Their rumps may also show striking blue and red coloration, which can help individuals communicate visually.

Mandrills live in social groups and eat a varied diet that includes fruit, seeds, leaves, fungi, insects, and other small animals. Large groups can contain many individuals, although their social organization may change with food availability and season.

They are sometimes confused with drills, their close relatives. Mandrills have more colorful faces and are generally more widely distributed in rainforest environments. Both species belong to the monkey family Cercopithecidae.