4. Forrest Gump
Box Office: $679,400,525 One of the most beloved movies of all time sees Tom Hanks playing the simple-minded yet affable titular character, as he makes his way through life unassumingly, yet changing history as he goes. The movie went on to win Best Picture at the Oscars, alongside awards for director Robert Zemeckis, lead Hanks, visual effects, editing and writing, and essentially became an overnight pop-culture phenomenon. Spurred on by the movie's success, Winston Groom, the author of the source novel, promptly released a sequel called Gump and Co. in 1995, which received positive notices from most reviewers. Why, then, has this never materialised into a movie? The script was finished in 2001, though after 9/11, writer Eric Roth, Zemeckis and Hanks apparently thought the story no longer relevant, even if studios have kept up a keen interest in it over the years. Given that the novel even incorporates the fact that a movie was made of Gump's life, and has Gump meeting Tom Hanks, it would surely make for an irresistibly funny movie.