From the BBC:

It is perhaps the most reproduced, recycled and ripped off image of the 20th Century.

Che Guevara, his eyes framed by heavy brows, a single-starred beret pulled over his unruly hair, stares out of the shot with glowering intensity.

It's now 40 years since the Argentine-born rebel was shot dead, so any young radicals who cheered on his revolutionary struggles in Cuba and Bolivia are well into middle age.

But the image has been infinitely repeated - emblazoned on T-shirts and sprayed on to walls, transformed into pop art and used to wrap ice-creams and sell cigarettes - and its appeal has not faded.

"There is no other image like it. What other image has been sustained in this way?" asks Trisha Ziff, the curator of a touring exhibition on the iconography of Che.

"Che Guevara has become a brand. And the brand's logo is the image, which represents change. It has becomes the icon of the outside thinker, at whatever level - whether it is anti-war, pro-green or anti-globalisation," she says.

Its presence - everywhere from walls in the Palestinian territories to Parisian boutiques - makes it an image that is "out of control", she adds.

"It has become a corporation, an empire, at this point."

The unchecked proliferation of the picture - based on a photograph by Alberto Korda in 1960 - is partly due to a political choice by Korda and others not to demand payment for non-commercial use of the image.

Birth of an icon

Jim Fitzpatrick, who produced the ubiquitous high-contrast drawing in the late 1960s as a young graphic artist, told the BBC News website he actively wanted his art to be disseminated.

"I deliberately designed it to breed like rabbits," he says of his image, which removes the original photograph's shadows and volume to create a stark and emblematic graphic portrait.

"The way they killed him, there was to be no memorial, no place of pilgrimage, nothing. I was determined that the image should receive the broadest possible circulation," he adds.

"His image will never die, his name will never die."