Gopher is the Disney-created Winnie-the-Pooh character who says he is “not in the book.”
He first appeared in the 1966 animated featurette Winnie the Pooh and the Honey Tree. The joke directly acknowledges that Gopher was not one of the characters in A. A. Milne’s original Pooh books.
Gopher was developed as an original Disney character and became a working, tunnel-digging resident of the Hundred Acre Wood. He is also recognisable for whistling his sibilant sounds, especially his “s” sounds. Howard Morris provided his original voice.
This detail helps distinguish the Disney adaptations from Milne’s books. Characters such as Piglet, Eeyore, Kanga, Roo and Tigger originated in Christopher Robin’s toys or the stories, whereas Gopher was invented for Disney’s animated productions.