I voted for The Shining, Rosemary's Baby, Shaun of the Dead (really more of a horror comedy than a horror movie per se), Nosferatu, eine Symphone des Grauens, and, in selecting Other(s), mean to represent Dario Argento's stylish and atmospheric 1977 Suspiria, starring Jessica Harper (one of my favorite actresses).
The Shining remains an underrated classic by Stanley Kubrick, which, while not the scariest movie imaginable, is certainly eerie and an undoubted example of an intelligent work of art within the genre. Rosemary's Baby shares this keen intelligence with a dash of quirky black humor, making an unsettling and memorable film. Shaun of the Dead (again, more of a comedy to my mind than a straight-out horror film) is delightful and compulsively watchable--Simon Pegg in the titular role, along with Nick Frost, are both absolutely charming. F.W. Murnau's silent masterpiece Nosferatu, eine Symphonie des Grauens is still probably the single greatest vampire movie ever made. And Suspiria, with its splendid Neo-Art Deco sets enhanced by the director's striking late use of Technicolor, combine with a marvellous prog-rock score by Goblin to create a vivid and unforgettable movie experience.