William Goldman
Screenwriter and novelist. Wrote ButchCassidyAndTheSundanceKid, ThePrincessBride, MarathonMan, and a bunch of other good stuff.
Also the author of Magic, which was turned into a very spooky movie starring Anthony Hopkins. There is another small novel told in the same vein as ThePrincessBride set in Venice: The Silent Gondoliers, written as S. Morgenstern. (S. Morgenstern is an invention of Goldman's, as is the family life described in the frame story of the Princess Bride novel.