The Silence of the Lambs
One of the most famous serial killer movies of all time, The Silence of the Lambs follows investigative FBI agent Jodie Foster as she tries to get some information out of Hannibal Lecter. Strangely, Lecter actually turns out to be a somewhat kind and empathetic serial killer cannibal, and he helps the FBI track down a murderer who steals the skin of young women.
Night of the Living Dead
Often referred to as one of the original scary movies, this film produced some truly gory scenes for a low budget without any CGI. It also touches on racial and social issues that remind us that there are still several horrors in our everyday life. Plus, this was one of the first mainstream "zombie" movies, despite being a bit more symbolic than your traditional brain-eating undead morons.