The "Harry Potter" author continues to profit from back sales of her iconic series, pulling in an estimated $14 million from Pottermore, the website through which she sells Harry Potter e-books. Notably, the author has not sold digital rights to the "Harry Potter" series, so she earns far more from Potter e-books than most authors do from digital sales. Her mystery novel "The Cuckoo's Calling," which was published under the pen name Robert Galbraith, became a bestseller last summer and her adult fiction novel, “The Casual Vacancy,” is also being adapted into a BBC miniseries.

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JK Rowling, author of the Harry Potter series, pictured in 2011.