The Sentinel (1976)

Around this time in the seventies there was a resurgence of films with demonic presences, amongst which were "Rosemary's Baby", "The Omen", and "The Exorcist". It was popular to give children the power of demonic powers, as they are vulnerable beings without much threat towards stronger adults. "The Sentinel" capitalized on the trend of giving demonic presence, but instead placed it within your home, where you supposedly feel safe. Instead of being a ubiquitous haunted house tale, the apartment in which model Alison is residing is the gateway into Hell, and though she believes she is surrounded by oddball, perverted, frankly creepy neighbors, she is all alone in the building except for a blind priest who lives upstairs. The film itself is not very horrific, doesn't try to be ultimately gory, and often tries to build up tension or show the depths of characters that aren't that interesting to begin with. Alison, our main protagonist, is living on her own since failing to commit suicide several times from being depressed as a teenager and from witnessing a gluttonous orgy brought about by her elderly father (it wasn't a pretty scene, and was probably the strangest part of a film that gets stranger as it goes). For over half of the film the model hears weird sounds, has problems concentrating and fainting, and seems stressed over her new home, but there is rarely a moment of true horror until the very end. Some seriously big names from the Golden Age of Hollywood show up in this including Ava Gardner, Burgess Meredith, Jose Ferrer, and Arthur Kennedy, in minor roles, some as demonic neighbors. The lead actress isn't horrible, but she seems out of her element on more than one occasion, looking bedroom eyed and confused. It has a really great concept, and the ending is creepy, but the film doesn't take its time to establish the concept or enlighten the audience, but instead traipses around making ghostly noises.