Notre Dame de Paris by Victor Hugo
Hugo wrote many books and poems, but is universally famous for just two works: Les Miserables and Notre Dame de Paris (commonly called the Hunchback of Notre Dame). They can be seen as two sides of the same coin: a love affair with Paris and the people of France. One book is the epic of French history, the other is the epic of the birth of modern France, both told through the lives of ordinary people.
"Ninety Three" by Victor Hugo
This could be called a prequel to Les Miserables. It does not feature any of the same characters, but it tells of a major event that is mentioned several times in the book: the Great Terror of 1793. 1793 in the reason why the people of Paris did not all support Enjolras and Marius in 1832 - they knew where it might lead.
The other books on this page are unauthorized sequels.
"Pont-Au-Change, Book One: Resurrections" by Arlene Harris
Judging by the reviews, this may be the best of the sequels. Perhaps because it does not come with the publicity of the other sequels, so people come with no expectations and are pleasantly surprised. Or perhaps because the author uses a different and unusual approach - it is not just a straight continuation of Hugo's novel. Readers praise Pont-Au-Change for capturing the spirit and the research of the original. It seems to me that these books are from someone who truly loves the originals, and is not just trying to make a buck from the success of the musical. Judge for yourself.
"Pont-Au-Change, Book Two: Sanctuary" by Arlene Harris
Just as the original was written in several parts, so is Harris' work.
"Pont-Au-Change, Book Three: Adrift" by Arlene Harris
The latest installment is part mystery novel. There are more installments on their way: visit pontauchange.com for the latest news.
"Cosette: The Sequel to Les Miserables" by Laura Kalpakian
In this book, Marius is involved in the 1848 uprising, and Cosette adopts a street child. Cosette has a daughter, Fantine, who of course falls in love with the boy. Some people liked the book, but Hugo purists hated it (of course). The consensus is that this is nowhere near as good as the original. How could it be? In particular it misses the political and philosophical edge of Hugo's work, and goes for a straightforward story instead.
"Cosette, or the Time of Illusions" by François Cérésa
This is the book that caused all the outrage. In this version, Javert did not die, but somehow survived, found God, and changed his life. The descendants of Victor Hugo (and most of Hugo's fans) felt that this went too far.
Les Miserables is out of copyright, but in France there is a law that the "integrity" of creative work can be protected forever. The Hugo family took this book to court, on the basis that it has Javert survive, which (they said) was an insult to the original book. They lost the first case, and won on appeal, but were only awarded token damages.
"Marius or the Fugitive" by François Cérésa
This was intended to be the sequel to Cosette, in which Marius is jailed for his anti-royalist views, and escapes. The Hugo family wanted it stopped before it appeared. As far as I can tell, they probably succeeded.
Are sequels always evil? My own view is that bad sequels will soon be forgotten, so no harm is done, but unauthorized sequels or rewrites are occasionally very good. Mutiny on the Bounty, the Aeneid, or several of Shakespeare's plays for example. Rewrites are usually rubbish, but sometimes, just sometimes, they can be good. I think we should allow the bad in order to have the good. But that's just my opinion.
Prequels and unofficial sequels
and the books they tried to ban