A list of the best selling book series of all time. These series are the best sellers of all bestsellers. Since religious and political books, such as The Holy Bible, are often given away for free, they have not been included on this list. These top selling book series span multiple centuries, covering many genres and original languages. And if you think Harry Potter or Twilight top this list, think again, they're not even close.What are the most popular book series of all time? What are the best selling books ever? The most famous books are indeed novels, with the most popular published volumes going through multiple editions and reprints. A few nonfiction texts can also be found, but they are few and far between. If one enjoys reading, these books are for you.