By Finlo Rohrer BBC News Online entertainment staff

Forty years after her body was found in a bungalow in Brentwood, Los Angeles, Marilyn Monroe still fascinates.

Audrey Hepburn, James Dean, Steve McQueen, John Lennon and Elvis remain celebrities beyond the grave, but most of all Monroe epitomises what it means to be an icon.

Often photographed, often impersonated, these stars shared good looks, unconventional lifestyles even by celebrity standards, and lives that ended tragically and prematurely.

Photographer and star get intimate

It is still Marilyn Monroe whose star shines the brightest. While other pin-ups, poster girls and primadonnas have faded in the public's collective consciousness, Monroe's image is as instantly recognisable as it ever was.

Her extraordinary photogenic qualities helped make a star out of her and she made names for the people who photographed her.

Just as Patrick Demarchelier and Mario Testino found wider fame by photographing Princess Diana, so Eve Arnold, Bert Stern and Douglas Kirkland greatly enhanced their reputations by capturing the screen icon.

Great insecurity

Many fans say they remain captivated by the mystery and complexity of Monroe's character.

She was an exhibitionist who was said to have slept with the Kennedys as well as many of Hollywood's most powerful men, but was also consumed by insecurity.

Fascination with her convoluted private life was exacerbated by a death that has led to four decades of murder conspiracy theories.

One of her last photo-shoots was with Kirkland, with Monroe naked except for a white sheet. The images are currently being shown for the first time in Britain.

This signed postcard fetched �3,500 at a recent Cooper Owen auction

Gallery owner Alex Proud agrees that the star's mix of power and vulnerability explained much of her appeal.

"When you see pictures of her it makes the hairs on the back of your neck stand up. She either has a genuine ethereal, magical, muse quality or I've been programmed to feel like that. I think it is the former.

"A lot of that might be down to her vulnerability. She was openly vulnerable whereas most of the icons of that generation had very protected PR.

"Douglas Kirkland said he never met a woman who so wanted to be loved."

Despite the magnetic quality of her modelling, many critics felt Monroe's performances as an actress were at best hit-and-miss.

Sensational as singer Sugar Kane in Some Like It Hot, but panned for many of her other performances, she became famous for late arrivals and a bad attitude to her work.

Kirkland's photos show a relaxed Monroe

Monroe memorabilia collector Stephen Vowles says her acting was underrated, insisting: "It takes a clever woman to play a dumb blonde."

Mr Vowles, who sells magazine advertising space, last week paid �3,500 at Cooper Owen's London memorabilia auction for a postcard signed by Monroe and admits it is her appearance and aura that still appeals.

"She was incredibly beautiful and the images of her are sensational. She made love to the camera, she knew what the camera could do for her, like Diana in a way. You could see the way the pictures changed.

"It was said it was like she walked into a room in slow motion. People tried to copy it and parody it but they never pulled it off.

"Her image is timeless. Her face is used on billboards all the time to sell products that weren't even thought of when she was alive."

Lifestyle pioneer

Other British fans of Marilyn Monroe will be joining those in the US and elsewhere to commemorate the 40th anniversary of the screen legend's death.

Among those paying tribute will be the UK's Marilyn Lives Society who are in Los Angeles for parties and memorial services celebrating the star's short life.

They will be remembering a woman who remains the archetypal celebrity-lifestyle pioneer, employing a personal trainer, jogging before it was a recognised pastime and following diets to control her fluctuating weight.

And as well as her ubiquitous visual legacy, Monroe marked an important trend in the history of film industry politics, taking on the declining studios and paving the way for the power of the modern actor, demanding in their working conditions and demanding over salaries.

Douglas Kirkland's pictures can be seen at the Elvis and Marilyn exhibition at the Proud Galleries, 5 Buckingham Street, near The Strand in London until 5 September.