Personally? I would have to say The Thing.
It's left completely open to interpretation. Debates still rage on whether Childs is human or not, for example.
S7ven is also noteworthy for that shock value ending.
#Horror #Scifi #Immortalis #movies

@Dexter I don't know about all time, but here are a few others that come to mind for me:

The first, another Carpenter movie, In the Mouth of Madness.

Others:
Fight Club
The Usual Suspects
The Menu
Midsommar

and as cliche as it might sound:
Citizen Kane

@Dexter I first watched Seven on broadcast television. It was heavily edited, obviously.

The way I remember the ending being edited, John Doe never said what was inside the box, and that was more disturbing than the theatrical release where he says it's Gwen's head. I always wish the theatrical had cut that line. I think it works better not knowing, but knowing that she is obviously dead...and that she was pregnant at the time... 😳

@Dexter Sleepaway Camp & Giallo are the first ones that pop into my mind.
@Dexter “The Thing” is my favorite movie, and the ending is just perfect.
@Dexter super from 2009. Just a perfect but unconventional end for the story