People have always been interested in finding the extreme limits of characteristics, both in ourselves and in our four-legged friends. We want to know who was the fastest, smartest, oldest – and yes, smallest and largest.

Check out these pups who represent the two ends of the size spectrum and see which dogs are considered our largest and smallest…

A Trio of Chihuahuas: Boo Boo, Miracle Milly, and Heaven Sent Brandy

Both these pooches are known for being the smallest dogs in the world – and they’re both currently living.

They’re also both Chihuahuas, though Boo Boo is a longhaired variety while Milly is shorthaired.

Up until late 2013, Boo Boo held the title of the world’s smallest dog by height. She stood at 4 inches. Milly took the title recently; she stands at 3.8 inches when measured from paw to backbone.

As for the shortest dog by length? In 2007, the Guinness Book of World Records recognized another Chihuahua named Heaven Sent Brandy as the smallest in this category. From nose to tail, she measures 6 inches.

One Big Dog: Giant George

George was a Great Dane who was known and recorded as the tallest dog ever. He weighed in at an astonishing 275 pounds.

George was 43 inches tall when measured from paw to shoulders. He was over 7 feet tall when he stood on his hind legs.

The Great Dane passed away in 2013 one month before his 8th birthday. No one has yet to claim his title of World’s Tallest Dog. The two previous record holders before George included two other Great Danes, Titan and Gibson.

Heavyweight Contender: Zorba

Giant George may have been tall, but his even his 275 pounds is put to shame by the world’s heaviest dog.

Zorba, an English Mastiff, was 8 feet 3 inches long and weighed a whopping 343 pounds.

For more record-breaking dogs, check out this BuzzFeed post that was created in honor of National Dog Day back in 2011. Then let us know if your four-legged friends come anywhere close to matching these extremes in height, weight, or length!