|First appearance||Horton Hears a Who|
|Voiced by|| June Foray|
Sour Kangaroo, aka Jane Kangaroo is a busybody and creator of the jungle's laws who is skeptical about the existence of the Whos and Whoville on a dust speck. She also is mother of Rudy Kangaroo, who thinks her to be very embarrassing.
She serves as the main antagonist of the film. As Horton's claims begin to drive her towards darkness, she believes that once other people start listening to Horton, they'll start to come to her with questions she won't be able to answer. In order to avoid this, she begins making deals with the Wickershams and the vulture hitman Vlad Vladikoff. As the film progresses, her aims start to shift towards crushing Horton's spirit and building up her own reputation. The Kangaroo is too dismissive of the products of imagination and creativity, even to the point where she keeps her son Rudy jammed inside her pouch. She believes that outside the "comfort" her ideas provide him, non-conformity and anarchy are minutes away from turning their ordered life into chaos. Yet, in the end, Horton's convincing changes her mindset.
In Seussical, she thinks Horton is crazy for talking to a speck of dust, spreading the news around and causing great trouble for Horton.
In the book she's a yellow kangaroo. In the film she is purple with turf of fur around her neck and long hair on her that stands up straight.