Hi, Emmy
I just can't believe that no one has suggested the very obvious - and greatest of all - "Halloween" - John Carpenter's original and best, from 1978 - which bears endless re-watching despite its "cult" over-exposure. It is a masterclass in how to achieve careful, slow-burning claustrophobic terror with almost no explicit violence, and a very limited budget. By contrast, it also shows the 'Saw' and 'Hostel' series to be the nasty, unsubtle, blood-soaked adolescent gore they really are. Watch it with the lights off, and you will NOT want to go upstairs that night.!! You have been warned. :)