Harry Potter And The Deathly Hallows
All hail the incredibly talented J.K. Rowling and her creation of Harry Potter. As the final book in the series, Deathly Hallows actually broke sales records as the fastest-selling book ever because within 24 hours of release, 15 million copies were bought.
Harry Potter And The Chamber Of Secrets
This is second book in the series which J.K. Rowling actually found difficult to write under fear that it would not live up to the same success as the first. However, despite her fears, 77 million copies sold!