The drill is a powerfully built forest baboon that lives in Cameroon and Nigeria. It has a large head, large muzzle, rigged face with big nostrils, but only a tiny stump of a tail. Their butts are brightly colored and when they get excited the skin becomes even more vibrantly colored. They may be slightly overshadowed by their cousins the mandrills who are even more colorful and a bit larger. The male drills are much larger (up to 45 pounds (22 kg)) than females and have big manes on their backs and shoulders.

The drill climbs well and sleeps in low branches in the trees but it is primarily a ground-dweller and moves on all fours. It is a troop animal and can live in family troops of 20 or more or bands of up to more than 200. Males dominate the troups and are very aggressive with their strong teeth and arms when defending.

Drills are expressive and communicate with different grunts, cries, and expressions. They eat a wide variety of plant matter, insects, and other small creatures. Their population numbers are very low and they are listed as endangered.