The One and Only Ivan is a children's novel written by K. A. Applegate and illustrated by Patricia Castelao. The book is about a silverback gorilla named Ivan who lived in a cage at a mall. The novel is written in first person from the point of view of Ivan, a gorilla. He meets Ruby, a baby elephant taken from her family, and she makes Ivan see their home—and his own art—through new eyes. When Ruby arrives, change comes with her, and it's up to Ivan to make it a change for the better.