Gojira (1954)
Since the new Godzilla film is a more or less direct sequel to the 1954 original, I decided to watch it again to get ready since I hadn't seen it in several years. Unlike the goofier sequels that came later, the original film was intended to be a dark, dramatic, scary scifi/horror story and 60 years later, it's amazing how effective it still is. Watching it with the knowledge that Godzilla himself is a metaphor for the bombing of Hiroshima, the scenes of massive destruction and the attempts at recovery afterward are chilling and the ambiguous nature of the ending leaves one with a genuine sense of unease. While often overlooked, primarily due to the aforementioned goofy sequels, I would argue that the original film is a genuine classic and stands among the greatest horror films of all time. If you've never seen it, climb out from under your rock and do so.