These primates aren’t just big, they practically count as roommates.
It’s not just gorillas bench-pressing logs in the jungle. Some primates are so hefty, they weigh more than your average teenager. Others could pass as football players if you squint hard enough and forget the fur. Most people picture monkeys swinging through trees like featherweights, but some of these animals are pushing serious poundage. These ten primates are built like brick houses, and some of them know it.
1. Proboscis Monkey
They look like cartoon characters with that long nose, but male proboscis monkeys average about 50 pounds, with females coming in closer to 25. What’s weird is that most of that bulk isn’t from muscle, it’s from their massive potbellies, which are full-time fermentation tanks, as reported by the World Wildlife Fund. Their complex gut is built to break down leaves and unripe fruits, which would wreck the average stomach. And despite that round torso, they’re surprisingly agile, launching themselves between treetops with real confidence.
2. Baboon
According to National Geographic, male chacma baboons can reach 90 pounds, with the largest ones clocking in slightly higher if they’ve had access to plenty of food and minimal predators. These guys carry that weight like linebackers with attitude. They’re social, loud, and aggressive when they need to be. Baboons have been seen taking on predators like leopards when traveling in groups. That mass isn’t just for show—it makes them one of the most intimidating monkeys across sub-Saharan Africa.
3. Mandrill
As stated by the Smithsonian’s National Zoo, male mandrills can weigh up to 119 pounds, and that includes a serious chunk of muscle packed onto a short, broad body. They’re the heaviest monkeys on Earth and have the strongest bite of any monkey species. Despite their clownish faces, they’re not built for humor. That coloration serves as a billboard that says “don’t test me.” Their weight also gives them the upper hand in dominance hierarchies, where size means everything.
4. Gibbon
They’re surprisingly heavy for such acrobatic little daredevils. Gibbons may look dainty while swinging like Olympic gymnasts, but the larger species can hit around 30 pounds. That’s all lean muscle stretched over absurdly long arms. Gibbons are technically the smallest apes, but they’re strong enough to defend territory and launch themselves across 50-foot canopy gaps. Their weight doesn’t seem like much until you see what they do with it. Most humans couldn’t do one pull-up. Gibbons live by them.
5. Bonobo
Often mistaken for smaller chimpanzees, bonobos actually average about 75 to 100 pounds in the wild. They’re leaner and more peaceful in their social structure than their chimp cousins, but they’re still strong, muscular, and athletic. That sleek frame isn’t about fragility. Bonobos can climb, sprint, and wrestle like it’s their love language. They also have long legs and slightly smaller heads, which makes their weight distribution a little easier to underestimate—until you try picking one up, which you shouldn’t.
6. Chimpanzee
Adult male chimpanzees typically weigh between 90 and 130 pounds, depending on their habitat and diet. They may not look like giants, but they have around five times the strength of a human in pound-for-pound comparison. Chimps use that bulk for climbing, tool use, and if needed, conflict. Their muscle density is off the charts, especially in their arms and shoulders. A chimp at full weight isn’t just heavy—it’s physically dominant in a way humans never evolved to match.
7. Siamang
The largest of the gibbons, siamangs can hit 30 to 40 pounds, which makes them heavier than most of their gibbon cousins but still lightweight compared to the big apes. Still, that doesn’t stop them from swinging through the forest with unbelievable grace. Their massive throat sac helps amplify their territorial calls, which can travel miles through the rainforest. That extra vocal gear adds a surprising bit of weight—and it’s not fat. It’s just acoustic power wrapped in fur.
8. Black Howler Monkey
This South American heavyweight can weigh up to 32 pounds, which doesn’t sound like much until you hear them scream. That iconic howl can carry for three miles, and it’s produced by a specialized vocal chamber in the throat that adds both sound and heft to their upper body. These monkeys are built like low-key gym rats, thick in the chest and neck. And they use their mass strategically—more weight equals more sound, which means better territory control.
9. Orangutan
Adult male orangutans can weigh up to 220 pounds. That’s an entire adult human in fur, swinging through treetops in silence. Their sheer size becomes more impressive when you realize they live mostly alone and navigate complex jungle environments without help. Their arms stretch longer than their own height, and they move like controlled cranes rather than clumsy climbers. That 220 pounds gets hauled across massive gaps in the canopy like it’s nothing.
10. Gorilla
Wild male gorillas can weigh between 300 and 430 pounds. That’s not a typo. And that’s not zoo bloat either—that’s straight forest muscle from a plant-based diet. Gorillas don’t run or chase, they stand and move like walls with legs. When silverbacks posture, it’s not for show. That weight has purpose behind it. Chest slaps aren’t just for intimidation—they vibrate the air around them, broadcasting dominance through both sound and presence.