Gopher was created specifically for Disney and does not appear in A. A. Milne’s original Winnie-the-Pooh books.
The character first appeared in the 1966 animated featurette Winnie the Pooh and the Honey Tree. Gopher was designed as a hard-working, anthropomorphic gopher with a distinctive habit of whistling his consonants.
In his first appearance, Gopher jokes that he is “not in the book,” directly acknowledging that he was a Disney creation rather than a character adapted from Milne. Disney initially developed him partly as a possible replacement for Piglet, but Piglet remained in the stories and Gopher was added as a new character.
Rabbit, Owl, Kanga and the other named examples originated in Milne’s books. Gopher later appeared in Disney television shows, specials and games, becoming familiar to generations of Pooh viewers.