There's the big dogs, and then there's the Leonberger. But don't be put off by their imposing presence. These big softies are full of love!
2. The Newfoundland
Newfoundlands were bred to go fetch nets that fishermen would drop in the water. Over the years, they've also been trained for water rescue. So it's no surprise that these big-boned dogs love the water...and they're fond of food too!
3. St Bernard
These furry giants were first used to rescue travellers stranded in the Swiss mountains. They've saved thousands of lives, which is why people started calling them Saints.
4. The Great Dane
The world's tallest ever dog was a Great Dane called Zeus. He measured a staggering 7ft 4 in tall when he stood on his hind legs. That's taller than the average professional basketball player.
5. English Mastiff
Some English Mastiffs weigh as much as 14-stone. So they're not the most agile dogs and they tend to take life at their own pace. Then again, when you're this big, who's going to tell you to hurry up?
6. Irish Wolfhound
These scruffy-looking big dogs have been around for a very long time. They even get a mention in the diaries of Rome's most famous ancient emperor - Julius Caesar.