The Lorax (voiced by Danny DeVito) is the Guardian of the Truffula Forest and the titular character of The Lorax. He speaks for the trees. He tries to tell the Once-ler to stop chopping down the trees because it's ruining the animal's home. When the last tree is chopped down, he sends the animals away to find another place to live, and goes up into the sky. When the trees are growing back thanks to Ted, he comes back with the animals and said he's proud of the Once-ler for doing something good, and comments on his mustache.
The Once-ler - When the Once-ler first came, the Lorax tries to get him to leave but the Once-ler refuses. They begin a friendship after he saves the Once-ler from falling down a waterfall when he puts his bed in the river. Soon when the Once-ler becomes greedy and selfish when his Thneed is selling like crazy after his family convinces him to go back to chopping the trees down, the Lorax tries to get him to stop again and remind him of the person he used to be and his promise. When the last tree is cut down, the Lorax becomes disappointed with the Once-ler because he ruined everything. When the trees are growing back, he returns and tells the Once-ler he did good and their friendship is restored.
Bar-ba-loots - He cares about the Bar-ba-loots. Espically Pipsqueak since he is the youngest. He sends them away when the Once-ler chops down all the trees.
Swomee Swans - He cares about them. He sends them away when all the trees are chopped down.
Humming Fish - He cares about the humming fish. He sends them away after all the trees are gone.
The Once-ler's family - The Lorax dislikes them because they made the Once-ler greedy and selfish and made him chop down the trees again.