While horror movies don't have to stray into R-rated territory to be scary, there is something oftentimes exciting about those that do. Horror, after all, is one genre that can find itself benefiting considerably from having as few restrictions as possible. And when it comes to the R-rating (or the equivalents outside America), anything deemed appropriate for those 17 and older is there for the filmmaker's taking, ensuring violence can be grislier, language can be more profane, and other adult content can be more than just implied.