The mutant primate is a large mutant created by Dr. M in Sly 3: Honor Among Thieves. When it first appears, the creature captures and is about to destroy Bentley, but Sly Cooper distracts it by throwing his cane into its mouth, which causes it to drop him. However, Sly is then immediately grabbed by the mutant, injuring him. While he is in its grip, Sly thinks back on the journey that got him to that moment. Soon after, Carmelita Fox arrives with her mercenary apes and fights the beast, causing it to release Sly.
Carmelita faces the mutant again after Dr. M detaches and later comes to save Sly within the Cooper Vault's inner sanctum. What happened to the mutant primate afterward is not explained, though it can be assumed that Carmelita defeated it.
It is a massive creature of unknown species, though due to the fact that Sly mentions that it is a genetic experiment, and that it appears to be a mixture of turtle or some other reptile and primate, it seems to be a hybrid. It has a green head, red arms, an orange torso and long claws. It wears a collar around its neck that Dr. M can plug into, presumably to control it. It also has metal pipes sticking out of its back that produce thick smoke, suggesting that it is somehow "powered" like a machine.
Being a genetic experiment by Dr. M, the mutant primate has little to no personality. It displays animalistic rage and does what Dr. M commands it to do, even when he is not connected via the collar around its neck.
It is very strong, as it can throw back the mercenaries with tremendous force, and seems almost unaffected by Carmelita's shock pistol.