Don’t Bother to Knock (1952): Marilyn’s first leading role, and her creepiest. She plays a psychotic babysitter recently released from a mental hospital in this confined, oddly compelling B movie. Her tentativeness as an actress meshes with the lost, dreamy girl she’s playing; even when she unravels completely, attempting to murder her young charge, she seems more victim than villain. With Richard Widmark and a very young Anne Bancroft as a hotel jazz singer.

Clash by Night (1952): Robert Ryan, Barbara Stanwyck and Paul Douglas are the stars of this Fritz Lang melodrama, based on a Clifford Odets play. It’s a so-so movie, but it shows us a Marilyn we haven’t seen before: purposeful, spunky, and quick on her feet. It’s the most normal, pathos-free character she’d ever play. Another rarity: her boyfriend, a young hunk played by Keith Andes, is treated as much as a sex object as Monroe is.

Niagara (1953): In this lurid, crisply made Technicolor film noir, drected by Henry Hathaway, Marilyn is a femme fatale plotting to kill her husband (Joseph Cotton) so she can run away with her lover. On the brink of stardom, she’s carnality incarnate. This is the only movie that strips her entirely of her sweetness and innocence: she’s one bad girl, and she pays for it.

Gentlemen Prefer Blondes (1953): This Howard Hawks shipboard musical, in which Marilyn was felicitously paired with Jane Russell, is the movie that made her a mega star. As the gold-digging, not-so-dumb dumb blonde Lorelei Lee, the breathy, twinkly Marilyn emerged as a deft comic actress and a surprisingly confident singer (Remember “Diamonds are a Girl’s Best Friend”?) It’s a fascinatingly unromantic musical in which the men are far more superficial, and unappealing, than the money-loving gals.

The Seven Year Itch (1955): The white dress, the New York subway grating, the glimpse of thigh: the only thing “classic” about this stage-bound Billy Wilder movie is that indelible image. Watching uncharismatic married man Tom Ewell lusting guiltily for the blonde bombshell upstairs for two hours no longer tickles the funny bone. Marilyn, however, manages to play a total tease and remain sympathetic, somehow convincing us she’s dizzily unaware of her devastating effect on men.

Bus Stop (1956): Shifting her voice into a shrill hillbilly whine, Marilyn gives a deeply touching performance as a third-rate saloon singer who falls in love with a rube cowboy played by Don Murray. Finally she gets a love interest her own age, but he’s such an infantile, overbearing jerk it’s hard to root for them to get together. Based on a William Inge play, this strenuously overacted Josh Logan movie has aged badly-except for Marilyn. Her deliberately awkward rendition of “That Old Black Magic” is magic.

Some Like it Hot (1959): Marilyn is at her most lusciously overripe as Sugar Kane in Billy Wilder’s hilarious cross-dressing comedy-easily the best movie she ever made. She may have driven her director mad with her tardiness and insecurities, but she repaid him with a performance that breathlessly mixes sexiness with child-like sweetness. Duped at every turn by Tony Curtis and Jack Lemmon, she somehow manages to maintain her ditsy dignity, and keeps the comedy floating on air.

The Misfits (1961): “You’re just about the saddest girl I ever met” says cowboy Clark Gable to Marilyn’s Reno divorc…e, and in the early scenes of John Huston’s movie Monroe has never seemed more damaged and melancholy-or more real. But husband Arthur Miller’s overwritten script transforms her into the life force itself, and she’s stuck playing a sentimental symbol in a murky treatise on the demise of the cowboy ethos. This death-haunted movie was the last for both her and Gable, but, sadly, these two screen legends from different eras didn’t mesh-they have no sexual chemisty on screen.