If you can't see, hear, or feel something, it doesn't exist. And believing in tiny imaginary people is just not something we do, or tolerate here in the Jungle of Nool. (Horton: Really? Cause I betta I really try to find somebody who believes what I’m saying.) You were nothing as I thought. You will not breathe a word of this lie to anyone else--especially the children! I don't want you poisoning their minds with this nonsense. Our community has standards, Horton. If you wanna remain a part of it, I'd recommend you follow them. Have a nice day.
~ Sour Kangaroo to Horton.
Jane Kangaroo, or more commonly known as Sour Kangaroo, is the main antagonist of the 1954 children's book Horton Hears A Who! by the late Dr. Seuss, the 1970 animated television special of the same name, the 1992 animated film I Can Hear You, the 2000 Broadway musical Seussical, and the defunct Blue Sky Studios' 4th animated feature film Dr. Seuss' Horton Hears a Who!. She also appears in the Horton Hears A Who! story in the 1996 live action/puppet TV series The Wubbulous World of Dr. Seuss.
Jane is a busybody and creator of the jungle's laws, who does not believe Horton the Elephant about the Whos and Whoville on the dust speck (mainly due to being under the misapprehension that anything which cannot be seen, heard or felt is nonexistent). She hires a vulture named Vlad to steal the clover bearing the speck for her. When he fails to do so, she orders her henchmen, a group of monkeys known as The Wickersham Brothers, to take the speck from Horton and intimidate him into saying that the Whos do not exist.
After everybody was able to hear the Whos, her son named Rudy jumped out his mother's pouch and gave the speck back to Horton, much to Sour's dismay, but in the end Horton forgives her despite everything she has done to him. She then joins Horton and the others in singing Can't Fight This Feeling Anymore.
Sour Kangaroo threatening Horton to be quiet about his belief in the speck–especially around the children.
Sour Kangaroo making a deal with Vladikoff.
"Shut up, mouse."
Kangaroo tells Horton
Sour Kangaroo's evil grin to Horton.
Sour Kangaroo's villainous breakdown.
She is the second main antagonist of a Blue Sky Studios film who is a parent, after Madame Gasket.
She is similar to Lots-o'-Huggin' Bear from Toy Story 3. They both are manipulative leaders, both have falsely imprisoned the protagonists, and both have attempted mass murder, but failed. - The only difference is Sour Kangaroo did it unknowingly because of her disbelief of The Who’s existence, while Lotso in Toy Story 3 attempted mass murder to the toys on purpose and did not redeem himself.
She is also the first main antagonist of a Blue Sky Studios film who is not killed off in the movie at all.
In addition, she is also the first main antagonist of a Blue Sky Studios film who redeems herself.
In the 2008 film, Allison Janney was considered for the role of Sour Kangaroo before Carol Burnett was cast.