1. Great Pyrenees
As its name suggests, the great Pyrenees was developed in the Pyrenees mountain range of France. It's a supremely good livestock-herding dog and is known to protect its charges, regardless of what they are, at all costs.
2. Shetland Sheepdog
Shetland sheepdogs, or shelties as they're affectionately known, are renowned for shadowing their owners wherever they go - including when they merely move into another room in the house! They're often reserved to the point of being shy around strangers, and live their lives devoted to their owners.
3. German Shepherd
It's no coincidence that these dogs are used by many military and police forces around the world - their defining trait is unwavering loyalty to their owners or handlers. They'll fearlessly drag a soldier out of harm's way in a war zone, defend their police handler with their life, or protect children from an intruder.
4. St. Bernard
The St. Bernard is a fiercely loyal dog breed that was developed for use in refuges for travelers traversing the snowy mountain passes between Switzerland and Italy. The breed was used as a guard dog, and to rescue travelers trapped in the Alpine snow.
5. Rough Collie
Often seen as the larger version of Shetland sheepdogs without the reserved nature, rough collies, or "Lassie" dogs, are as loyal as they come. They're also selfless dogs - they won't just attempt to save a family member in need, but anyone at all who's in need. They also like to shadow their owners or handlers, just as shelties do.
The Kuvasz was bred for Ottoman sultans, and its name actually means "armed guard of the nobility" in Turkish. Although they're somewhat aloof dogs, even when it comes to their own families, kuvasz are the most devoted of protectors.
The Akita is a Japanese breed that is known for its undying loyalty. They are highly intelligent and very strong-willed, but they'll stop at nothing to protect their family.
Brittanys make superb hunting dogs and are known to follow their owners to heel for miles upon miles. Although they're primarily used for that purpose, their devoted nature makes them great dogs to train for use in any sport.
9. American Staffordshire Terrier
American staffies will do just about anything for their owners, but their highly loyal nature has a downside - they make good fighting dogs purely for that reason. They'll do as they're told regardless of how it is they've been treated, or what it is they're being asked to do.
Mastiffs, specifically Neapolitan ones, were developed millennia ago in southern Italy, and Julius Caesar himself had one. They've been used in wars, to protect palaces, to guard livestock and guard homes. Despite their fearsome size and appearance, they're known to be gentle giants around their respective families.