The St. Bernard Dog is a large dog originally bred for water rescue and as a working dog. It is known for its loyalty and vigilance and is tolerant of children, animals, and strangers. Because of those traits, it has become a family dog.

The origin of the St. Bernard cannot be fully determined. Formerly, they were the herding dogs of Swiss farmers as well as hunting dogs and watchdogs. Their history has also been connected with the hospice at the St. Bernard pass. First reports of the dogs' presence at the pass date to the 17th century, and they still are loyal companions to the monks there.

The name "St. Bernard" was not in widespread use until the middle of the 19th century. The dogs were called "Saint Dogs", "Alpenmastiff" or "Barry Dogs" before, and in parts of North America, they're still called "Saints".