While not a poster, I came across this OOP hardcover copy of
The Phantom of the Opera, published in 1988 by Unicorn Publishing House, Inc, and which was illustrated by the amazing Greg Hildebtandt of
Star Wars poster fame and others.
He did 32 color and B/W illustrations for the book. I've included the cover art, which is also a plate in the book, and one other.
The original book was published in 1909, with the original title,
Le Fantôme de l'Opéra, and was written by Gaston Leroux.