No, Boxers are not naturally aggressive. Properly bred, socialized, and trained Boxers often have friendly, playful dispositions towards people and other animals. However, Boxers have a protective instinct and may display territorial behaviors if they perceive a threat to their families or homes.
If you are concerned by any signs of aggression or reactivity in your dog, be sure to address it promptly with the help of a professional trainer or behaviorist. Pain, discomfort, or underlying medical conditions can sometimes contribute to changes in a dog’s behavior, so it may also be worth visiting a vet to rule out their health as a cause for signs of aggressive behavior.