9. Dewey - Scream
Loveable goofball cop Dewey Riley (David Arquette) is essentially the heart and soul of the Scream movies, providing comic relief and some much-needed humanity amid the slasher film scenario. While by this point in the franchise it seems like he's indestructible, having survived near-death four times, he was originally written to die at the end of the first Scream. However, test screenings liked the character a lot, and wanted to see him make it to the end of the movie, so Wes Craven had to quickly cobble together an additional scene that showed Dewey being loaded into an ambulance on a stretcher, which slots effortlessly into the final product. This is one of the few changes that is 100% right; Dewey's such an enjoyable component of these movies that they'd feel a little empty without him. Granted, many likely expected
him to die - how often does the comic relief survive? - but that's just another way the Scream franchise bucks convention.