The Once-ler's Mother has short curly blonde hair with a tiny red bow clipped on it. She wears big black glasses, a pink sweater with white polka dots, a long denim skirt, fur stole and turquoise boots.
She is moody, spoiled, lazy, snide, money-crazy, greedy and failure-intolerant. She is manipulative and abusive to the Once-ler.
She went to help the Once-ler make Thneeds. It was her and the rest of the family that persuaded the Once-ler to chop trees down rather than harvest their tufts. She was proud of him only when he became greedy and self-righteous. But when the Thneed factory closed because of no more trees, she disowned him and told Bret that he is now her favorite child. She then left the Once-ler to be a hermit.
- Once-ler - She treats him very sarcastically and told him that he would fail in his life for untold reasons. When his business fails she promotes other sons to her favorite child.
- Brett and Chet - The mother seems to treat them both nicely at times. She promoted Bret to her favorite child, when the Once-ler failed.