Best-selling refers to the estimated number of copies sold of each book series, rather than the number of book series printed or currently owned. Sales numbers for religious and political book series are nearly impossible to track because many are given away by churches or governments. Additionally, these kinds of book series may be produced by many different and unrelated publishers, in some cases over many centuries., many of them unreported. For these reasons, major religious and political texts are not listed here.
Here are the top 20 best-selling book series in history.
| Rank | Book series | Author | Estimated sales |
| 1. | Harry Potter | J.K. Rowling | 500 million |
| 2. | Goosebumps | R.L. Stein | 300 million |
| 3. | Perry Mason | Erle Stanley Gardner | 300 million |
| 4. | Berenstain Bears | Stan and Jan Berenstain | 260 million |
| 5. | Choose Your Own Adventure | Various authors | 250 million |
| 6. | Sweet Valley High | Francine Pascal | 250 million |
| 7. | Noddy | Enid Blyton | 200 million |
| 8. | Nancy Drew | Carolyn Keene | 200 million |
| 9. | Thomas the Tank Engine | W. Awdry | 200 million |
| 10. | San-Antonio | Frédéric Dard | 200 million |
| 11. | Robert Langdon | Dan Brown | 200 million |
| 12. | The Baby-sitters Club | Ann Martin | 172 million |
| 13. | Star Wars | Various authors | 150 million |
| 14. | Little Critter | Mercer Mayer | 150 million |
| 15. | Peter Rabbit | Beatrix Potter | 150 million |
| 16. | Chicken Soup for the Soul | Jack Canfield and Mark Victor Hansen | 130 million |
| 17. | American Girl | Various authors | 120 million |
| 18. | The Chronicles of Narnia | C.S. Lewis | 120 million |
| 19. | Mr. Men | Roger Hargreaves | 120 million |
| 20. | The Twilight Saga | Stephenie Meyer | 120 million |
| Diary of a Wimpy Kid | Jeff Kinney | 120 million |
