Se7en

It consists basically of a detective (a cop drama) movie, blending with influences of:  thriller,  represented in the constant tension created throughout the film in a nearly claustrophobic way; mystery, shown in the solving of a complex crime; serial killer-horror in the display of extreme gore of the crimes and their brutality; also, the influence from Noir mood or movement is very clear (although this is not a genre), as the atmosphere throughout the whole movie is a dark, menacing one. In cop drama conventions, we see both stereotypal characters being the experienced and the young one, and the contrast between them.