In 1605, Miguel de Cervantes published a book, "The Ingenious Gentleman Don Quixote of La Mancha" (now typically known simply as "Don Quixote"). It was (and remains to this day) quite popular.
In 1614, an anonymous other author published a book, "Second Volume of the Ingenious Gentleman Don Quixote of La Mancha", without permission. Cervantes was quite upset, particularly with the portrayal his characters received in this book.
Of course, our modern Copyright laws didn't arrive until the 18th century. And even now, the usage of other people's characters in an original work is a bit murky, particularly when their core qualities are changed. So Cervantes couldn't make a legal challenge on the basis of copyright, the way that we can today.
Instead, Cervantes published his own sequel in 1615 (now typically printed together with the original book), in which miscreants unknown are alleged to have travelled around the country, pretending to be the book's chief protagonists, Don Quixote and Sancho Panza (thus explaining their uncharacteristic behaviours described in the unauthorised book).
To stop future authors from producing further derivative works using his characters, Cervantes has Don Quixote die at the end of the second book, and informs readers that since Don Quixote is now dead, any Don Quixotes which may appear in further books must therefore be fraudulent ones.
....so you could always do that. :)