22. Se7en (1995)
Se7en is a very dark detective story, and an underappreciated highlight of the horror genre. The tone, the attitude, and the visual palette of David Fincher's noir simply screams "horror story" to me. Before you argue, think about the crime scenes, the eternal rainstorms, and the mercilessly intense third act, and then tell me that Se7en isn't, in some large way, a horror film. And a really amazing one, too.