3. Agatha Christie
Agatha Christie is the author has reportedly sold more books than the other two authors combined.
Agatha Christie is the best-selling novelist of all time. She is best known for her 66 detective novels and 14 short story collection.
Her novels are sold more than 2 billion copies worldwide. The Guinness World Records lists Christie as the best selling fiction writer of all time.
On than other hand, J.K.Rowling who is the creator of Harry Potter has only sold about a quarter as many books as Agatha Christie.