Roo is a fictional character created by A. A. Milne and first featured in the book Winnie-the-Pooh. He is a young kangaroo, the son of Kanga.
Because of his young age, Roo is a very small animal, the smallest in the story (other than Rabbit's friends and relations, and Alexander Beetle), although he must be very close in size to Piglet since Kanga is unable to tell the difference when Piglet jumps into her pouch instead of Roo. (In Ernest H. Shepard's illustrations, Roo appears to be very slightly smaller than Piglet.) He is also apparently small enough to fall down mouse holes while practicing jumps, and too small to reach the first rail of the Poohsticks bridge.Like most of the characters in Winnie-the Pooh, Roo was based on one of Christopher Robin Milne's stuffed toys.