Film noir, like its protagonists, is hard to pin down. Is it a genre? A style? An attitude? A worldview?

Well, noir can’t be confined to a genre, surely. After all, the look and feel that we recognize as noir has a kind of alchemical effect, transforming and enriching films that seem to belong to established genres or categories.

On this list, you’ll find so-called women’s pictures (see The Letter, Mildred Pierce, Nora Prentiss), a horror movie (Cat People), and a period thriller (Reign of Terror). I’ve even included the Technicolor melodrama Leave Her to Heaven, which Martin Scorsese calls “a film noir in color,” since it proves that noirish decadence can inhabit the sunniest and serenest of places. Despite their many differences, all of these films are located somewhere on the noir atlas. Watch them and behold the flexibility of noir in action.

Whatever it is exactly, noir wants to be noticed. It refuses to respect the harmonious, self-effacing style that classical Hollywood typically embraced.

Expressionistic shadows (The Letter, The Stranger on the Third Floor) evoke the brooding, nocturnal fears of the protagonists. Low-key lighting (Out of the Past, Sunset Blvd., The Killing, and most screenshots here) adds striking contrasts to images, amping up the tension of any scene. Reflections (The Lady from Shanghai, The Narrow Margin, Touch of Evil) cram the frame with information and overwhelm the viewer with a choice of objects to look at. Characters break the fourth wall or come close (Shadow of a Doubt, Gun Crazy), aggressively invading the audience’s world.

I’ve tried to capture a diverse selection of films noirs in terms of budget, from prestigious productions with big-name stars (like MGM’s The Postman Always Rings Twice and Paramount’s Double Indemnity) down to obscure thrillers made at “Poverty Row” studios (like PRC’s Detour, Monogram’s Decoy, and Republic’s The Spector of the Rose). Yet, as the shots show, these films exemplify a kindred beauty, a dark, impossible-to-ignore splendor.

This selection also focuses on American films noirs made during the classic Hollywood era (pre-1965). That said, if the AFI can count The Third Man as an American film, then, damn it, so can I. Please don’t think of this list as anything like a definitive catalog of films noirs. I had to eliminate a number of personal favorites (The Stranger, The Blue Dahlia, The Dark Mirror) to get a sample of 50.

So, without further ado, mugs and molls, let’s go down those dark, crooked streets together.

THE LETTER (1940)

Director of Photography: Tony Gaudio | Director: William Wyler

THE STRANGER ON THE THIRD FLOOR (1940)

Director of Photography: Nicholas Musuraca | Director: Boris Ingster

I WAKE UP SCREAMING (1941)

Director of Photography: Edward Cronjager | Director: H. Bruce Humberstone

THE MALTESE FALCON (1941)

Director of Photography: Arthur Edeson | Director: John Huston

THE SHANGHAI GESTURE (1941)

Director of Photography: Paul Ivano | Director: Josef von Sternberg

CAT PEOPLE (1942)

Director of Photography: Nicholas Musuraca | Director: Jacques Tourneur

THIS GUN FOR HIRE (1942)

Director of Photography: John F. Seitz | Director: Frank Tuttle

SHADOW OF A DOUBT (1943)

Director of Photography: Joseph A. Valentine | Director: Alfred Hitchcock

DOUBLE INDEMNITY (1944)

Director of Photography: John F. Seitz | Director: Billy Wilder

LAURA (1944)

Director of Photography: Joseph LaShelle | Director: Otto Preminger