Sometimes, things are better left to the imagination. Better yet, left to the imagination of the writers conjuring up those on-screen horrors that leave an indelible mark on our psyches; terrible things we didn't know we'd witness, things we'd maybe not even considered before. Imagine a world where you'd never watched The Godfather. You'd not have seen that guy wake up to find a horses head in his bed. Did you know that was a real head used in that scene? Knowing this fact made me want to unsee that moment. Or what about the eye-gouging in 28 Days Later (reprised to even more sickening effect in the sequel, 28 Weeks Later)? Yuck. It's those kind of images - the ones that give cause to sit up, or wince in your seat, or avert your eyes suddenly (inevitably freezing that last vision in your brain forever). The following list represents my top examples. I've applied some rules, though - no torture porn (the sub-genre is built around the whole premise you'll see some things you wish you hadn't, so that's too easy); for the same reason, no extreme Asian cinema. I also ruled out shorts or experimental films (sorry, no Brunel eye-slicing). Oh, and no cannibal or serial killer movies. Before you begin: those of you who are squeamish be warned - some of these entries will contain graphic descriptions of unpleasant/disturbing scenes!