Entertainment

New blonde bombshell

Many actresses have played Marilyn Monroe, on big screens and small, since her death nearly 50 years ago. They’re all cheap impersonators compared to Michelle Williams’ extraordinary performance as the doomed ’50s sex bomb in “My Week With Marilyn.’’

Scheduled to hit theaters Nov. 4 after its world premiere at the New York Film Festival on Sunday night, this film is basically an entertaining, lightweight romantic fantasy. Advance Oscar buzz about Williams’ layered and touching work is correct, though: She may resemble Monroe less than many impersonators, but Williams gets under the skin of the troubled yet manipulative screen icon in a way no one else has.

“It was a very, very slow process,’’ Williams said in a press conference. “I started watching movies, listening to interviews, poring over books. In my living room, I would mimic a walk and figure out how exactly she was holding her mouth.

“My first big discovery,’’ Williams continued, “was that for Marilyn herself, ‘Marilyn Monroe’ was a character she played. The image she carefully honed was artifice. It was honed to where you couldn’t tell it was artifice.’’

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Indeed, one of the film’s most charming moments is when Williams’ Marilyn whispers to a companion, “Shall I be ‘her’ ?’’ before sashaying in front of a delighted group of employees at Windsor Castle.

In her tour de force, Williams effectively plays three parts. In addition to this publicly flirtatious Marilyn, there’s the insecure diva who wreaks havoc on the set of “The Prince and the Showgirl’’ in 1956 England — enraging her haughty director and co-star, acting legend Sir Laurence Olivier (a hilarious Kenneth Branagh).

When her frustrated new husband, playwright Arthur Miller (Dougray Scott) abruptly leaves on a visit to the United States, Marilyn — perennially late and often forgetting lines in a fog of pills and booze — stops showing up for work altogether.

Olivier sends his third assistant director, 23-year-old Colin Clark (Eddie Redmayne), to check up on her.

According to a disputed 2000 memoir by Clark — son of the famed art historian Sir Kenneth Clark (TV’s “Civilisation’’), a longtime friend of Olivier and his wife, Vivien Leigh (Julia Ormond) — on which the film is partly based, this led to a daylong outing together, and two nights spent (chastely) in her bed.

Even if you don’t buy this as true — I don’t — these scenes are the most charming in the film. At one point, Marilyn, then 30, talks Colin into skinny-dipping with her in the Thames, remarking, “This is the first time I’ve ever kissed anybody younger than me.’’ There is also a visit to Colin’ s school, Eton, as well as the Windsor Castle tour conducted for the wide-eyed Marilyn by the royal librarian (Derek Jacobi), who happens to be Colin’s godfather.

Following this escapade, Colin is warned to stay away from Marilyn by her business partner Milton Greene (Dominic Cooper), a pill-dispensing former lover whose life savings are tied up in “The Prince and the Showgirl,’’ the first film from Marilyn Monroe Productions.

But it’s Colin who is urgently summoned when Marilyn locks herself in her bathroom after a miscarriage. Despite such darker moments, “My Week With Marilyn’’ maintains a fairly breezy tone for much of its brisk length, thanks to Simon Curtis, a veteran British TV and theater director making his feature debut.

Judi Dench appears as the veteran actress Dame Sybil Thorndike, who encourages Marilyn on the set — and chastises the aging Olivier, who is jealous of her magical screen presence. Olivier is also fuming because Marilyn is receiving on-set coaching from Method acting guru Paula Strasberg (Zoë Wanamaker).

In fact, largely because of Olivier’s stodgy direction and acting, “The Prince and the Showgirl’’ was a box-office flop — despite one of Monroe’s most charming performances.

More than half a century later, audiences may well be more intrigued by “My Week With Marilyn,’’ which uses that problematic movie as its background.

Even more ironically, Williams (who also beautifully performs three musical numbers as Marilyn) may eventually go home with an Oscar — for playing an actress who was never even nominated.