Eponymous – Character in a play or book whose name is the title of that play or book
A pony called mouse (eponymous) is the title of the book; guess what the book is about? The title is also the main character.
Examples of eponymous in a sentence
There are several designers who make their clothing lines eponymous by naming the lines after themselves.
The singer's first album was eponymous and carried her name as the record title.
In the film the hero, for whom the eponymous movie is named, saves everyone from a horrible disaster.