All are among the largest of monkeys. They all possess large ischial callosities. In guinea baboons these are bright red. Baboon ears and faces are naked. Forelimbs and hindlimbs are about equal in length.
Tails vary, but are generally long.
Their fur is dense and their coloring varies somewhat, though most coats contain grey or brown. Body lengths range between 50-60cm. They are sexually dimorphic in size and appearance, with males being larger, often twice as large, and having a more distinctive appearance. This is especially pronounced in the hamadryas subspecies. This added coat enhances the males' appearance, making them seem even larger.