The Olive Baboon is named for its coat, which, at a distance, is a shade of green-grey. (Its alternate name comes from the Egyptian god Anubis, who was often represented by a dog head resembling the dog-like muzzle of the baboon.) At closer range, its coat is multi-colored, due to rings of yellow-brown and black on the hairs. The hair on the baboon's face, however, is finer and ranges from dark grey to black. This coloration is shared by both sexes, although males have a mane of longer hair that tapers down to ordinary length along the back. Besides the mane, the male Olive Baboon differs from the female in terms of size and weight. Males are, on average, 70 cm tall and weigh 24 kg; females measure 60 cm and 14.7 kg.

Like other baboons, the Olive Baboon, does not have a flat face, but a long, pointed, dog-like muzzle. In fact, along with the muzzle, the animal's tail (38–58 cm) and four-legged gait can make baboons seem very canine. The tail almost looks as if it is broken, as it is held upright over the rump for the first quarter, after which it drops sharply. The bare patch of a baboon's rump, famously seen in cartoons and movies, is a good deal smaller in the Olive Baboon. The Olive Baboon, like most cercopithecines, has a cheek pouch with which to store food.

Photo: Olive Baboon (Papio anubis) in Kenya