A Tale of Two Cities, The #1 bestselling book of all time, is written by Charles Dickens and is sued in many English classes. Interestingly, The Little Prince(French - Le Petit Prince), and Dream of the Red Chamber(Chinese - 紅樓夢) are the only non-English titles in the top 10. Harry Potter managed to appear twice, speaking to the widespread popularity of the series. In fact, Harry Potter has been translated into 79 different languages, which would thus lead to more book sales.
On a side note, an interesting aspect of Harry Potter's success is the creative way's translators of the book series have managed to keep the linguistic jokes and features of the series, like making acronyms make sense in the translated language while also maintaining their connotations.