I am not talking of book sales, although Lee's Pulitzer prize-winning novel is one of the most popular books of all time.

We haven't found a list, but a check of the Guinness World Records' entry for Best-selling Fiction Author finds Agatha Christie at the top, with an estimated 2 billion copies of her works sold.

Stephen King is a writer best known for his horror and fantasy novels. He has written over 50 best-selling horror novels, such as 'Carrie', 'The Shining' and 'Dreamcatcher'.