Cure
By far my favorite horror movie ever made. I’ve always felt you can split identity into three parts, that being how others perceive you, how you perceive yourself, and the subconscious. Not any one part being more true than the other, but the latter being the most "powerful" per say. And being that, to me anyway, it’s the most terrifying as well. Not many pieces of media can actually translate that terror perfectly into art, but cure does just that.