15) 15. Tibetan Mastiff: Independent and Highly Suspicious
Tibetan Mastiffs are legendary for their independence and strong guarding instincts. They were bred to protect property and livestock, so they naturally take watchfulness seriously. Under stress, they can become deeply territorial and very hard to persuade once they decide something is a threat. They are not typically eager to please, which makes early, thoughtful training especially important. Their suspicion of strangers can be a strength in the right setting, but a liability in a busy household. Owners who respect their boundaries and provide stable leadership are more likely to get a calm, balanced guardian.