An all-time classic, I doubt I'm going to say anything about this you haven't heard before.
For those who haven't seen it, Rosemary and Guy Woodhouse move into a new apartment (played on the exterior by the Dakota apartments where John Lennon was killed). They find their new neighbors very intrusive and, when one mysteriously dies, Rosemary starts getting concerned that they might not be the sweet collection of old eccentrics they claim to be. The real fun starts when Rosemary becomes pregnant after a night of nightmarish hallucinations (or were they?) and begins to believe that her neighbors are part of an evil cult who want to hurt the baby.
There is some great paranoia here, mixed with just the right amount of explaining away weird behavior. Charles Grodin plays a concerned doctor, John Cassavetes is the husband who finds his career taking off after making some deal with the neighbors, and Mia Farrow is excellent as the woman driving herself to the brink of madness. I'm glad this randomly turned up as close to Get Out as it does because they both explore some themes of "who can you trust?" that turn out very differently. All the performances ride that line between "creepy" and "weird but harmless." Polanski (problematic man at best) directs the crap out of this, allowing just enough of the viewer's imagination to creep in to scare yourself. For example, I could swear we see the baby at the end but, in reality, I don't think we do. I have a strong image of it in my mind, however (just like the robbery from Reservoir Dogs we never see).
I don't want to give too much away in case you've never seen it but I would like to sometime take a look at conspiracy in narrative (whether real or imagined). As is, I will just say, check it out.