Remember the frenzy when Harry Potter books and movies came out? Fans may be cast under a similar spell now that J.K. Rowling has agreed to write the screenplay for a Potter spinoff. (This 2005 photo was taken in London when the book Harry Potter and the Half-Blood Prince was released.) Paco Serinelli /AFP/Getty Images hide caption

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Looking a little mysterious: J.K. Rowling in the stands at the Wimbledon Lawn Tennis Championships last month. Julian Finney/Getty Images hide caption

itoggle caption Julian Finney/Getty Images