Bosco

Bosco the bear was the Earth King's pet. He resembles today's northern grizzly bear.

Behavior
Bosco was very ill-mannered, loud, and slobbery, and could often be seen eating. However, the Earth King apparently did not notice this, and treated him like his son. He now travels with the Earth King undercover to see the world outside the walls of Ba Sing Se.

Behind the scenes
When Bosco the bear is first mentioned to Aang and his friends in "City of Walls and Secrets", they are skeptical that there is such a creature as a "bear," and suggest that perhaps it is another type of creature, such as a Platypus Bear. This is an inside joke, as most of the animals in Avatar: The Last Airbender are either mythical or hybrids of two different animals from the real world.