Mula

Mula is Avatar Wan's animal companion and a cat deer. Wan first freed her from a trap, set by people looking to eat her. From that day on Wan and Mula became close friends.

History
When people from Wan's hometown were in the Spirit Wilds hunting for food, Wan saw her trapped. He freed her from the trap, and since then they shared a close bond. As Wan traversed the world, looking to learn the elements in order to defeat Vaatu, Mula journeyed with him.

Trivia

 * Mula is reminiscent of the red elk Yakul from Hayao Miyazaki's Princess Mononoke, of whose the films series creators Bryan Konietzko and Michael Dante DiMartino are professed fans. In the film, which also deals with conflict between humans and forest spirits, Yakul similarly serves as a mount for the protagonist, the banished Prince Ashitaka.