Melvin

Melvin is the name of The Once-ler's pet brown and white mule, as he accompanied him on his journey to find the material for his Thneed.

Melvin is shown to be loyal to his owner as he pulled the wagon, woke him up when they came across the Truffula Valley, staying and sleeping outside The Once-ler's house-like tent, hence being tied to a tree or a peg to keep him from wandering off. At the part where The Lorax with the help of the Bar-ba-loots, Humming Fish, and Swomee Swans planning to take his owner's bed and shove him into the river, Melvin curiously "asked" them what they were doing to his two-legged friend, but that's before The Lorax fed him a Truffula fruit causing him to not mind what they were doing to his owner at all.

But after the last of the Truffula Trees were cut and turning the Truffula Valley into a wasteland, he was not pleased by his owner's greedy actions, thus he joined the homeless animals as they left their once beautiful home and went to look for another place that they could call home, leaving his now-former owner and friend behind, alone in the land that his greed had destroyed.

Trivia

 * After Melvin abandoned his owner, The Once-ler, it is unknown what happened to him.