Mostly, the Great Danes show very gentle and friendly behavior. They may not disturb the owners. But in very few situations, the dogs can become protective. The Great Danes are very calm and well-mannered dogs; therefore, most animals keep them as pets.  But just like other dogs, they may show a very strange or weird behavior at some times. For instance, when they see an unknown person or a guest, they can start barking or show aggressive behavior. While on the other times, they will not show any strange behavior.