Bear and Cat

How Muschi the cat got into Mausi the bear's enclosure at the Berlin Zoo in 2001 is still unknown, but the two now share a living space and can't stand being apart.
Dog and Duck

When Dennis the duckling lost his mother to a fox, Fred the yellow labrador stepped in to take over parenting duties.
Tiger and Piglets

Saimai the tiger was raised by a sow, so it's no surprise that she bonded with some piglets at a tiger farm in Thailand.
Cheetah and Dog

Kasi was an orphaned cheetah cub, and Mtani a rescued Labrador pup when they were socialized together at Busch Gardens Tampa Bay. Turns out that the two were an excellent match and have been zoo mates and best pals ever since.
Image via Busch Gardens Tampa Bay & Adventure Island
Dog and Kangaroo

A German Pointer named Rex discovered a joey in the pouch of a kangaroo that was hit and killed by a car in 2008. Rex brought the joey to his owner, who then named him Rex Jr. and took the little marsupial to a wildlife sanctuary. The sanctuary later released Rex Jr. back into the wild.
Gorilla and Bunny

Eager to offer 47-year-old Samantha the Gorilla some companionship, the Erie Zoo gave her a rabbit named Panda. Now the gentle gorilla pets and feeds her new companion, and she has a best friend to spend time with.
Hippo and Turtle

Orphaned by a tsunami, Owen the hippo was moved to Haller Park in Kenya and placed in a enclosure with Mzee, the Aldabra giant tortoise. The 130-year-old reptile gladly accepted the new companion and the pair became inseparable.
Dog and Owl

When Shrek the owlet came to live in the same home as Torque the dog, the baby bird had free reign of the house. Soon enough, she was sneaking snuggles on the sofa with her new pooch pal while also watching TV.
Giraffe and Ostrich

At Busch Gardens Tampa Bay, you'll find Bea the giraffe and Wilma the ostrich walking around their enclosures and nuzzling noses.
Snake and Hamster

Aochan the rat snake formed a surprising bond with a hamster that was supposed to be dinner. The two share a cage at the Tokyo Zoo, and the hamster is now known as Gochan.