This entry on the list might be cheating a little bit but so what? Before Steven Speilberg filmed his family friendly classic E.T. The Extra Terrestrial started out as a movie about a family on a farm who are visited by a terrifying grey alien who would cause some havoc. Screenwriter Melissa Mathison came on board and did rewrites until we went from terrifying alien abduction film into the cute film that we all remember from our childhood. One cant help but to wonder what a ET horror film would look like. Blood, guts and Reeses Pieces everywhere. Well, that just sounds awesome!