Founder of ethical cosmetics firm Body Shop, Dame Anita Roddick, has died at the age of 64.
Dame Anita brought ethically-sourced products to the High Street
Her family said in a statement she suffered "a major brain haemorrhage" at 1830 BST at St Richard's Hospital in Chichester, West Sussex.
Her husband, Gordon, and daughters Sam and Justine were all with her.
Dame Anita set up the first Body Shop in Brighton in 1976. She pioneered cruelty-free beauty products and turned them into a highly profitable business.
In February she announced she had contracted Hepatitis C from a blood transfusion in 1971.
She had been taken to hospital on Sunday evening after she collapsed complaining of a headache.
'Force for good'
Prime Minister Gordon Brown paid tribute to Dame Anita, calling her "one of the country's true pioneers" and an "inspiration" to businesswomen.
He said: "She campaigned for green issues for many years before it became fashionable to do so and inspired millions to the cause by bringing sustainable products to a mass market.
"She will be remembered not only as a great campaigner but also as a great entrepreneur."
The Body Shop became part of the French company L'Oreal Group in July 2006 but is run independently.
The daughter of Italian immigrants, Dame Anita became one of Britain's most successful businesswomen.
She was the first to introduce socially and environmentally responsible business onto the High Street and she was talking about fair trade long before it became a buzz word.
Body Shop - with its ethically-sourced products - was one of the icons of the High Street in the 1980s.
Its fortunes had been hit in recent years as rivals started making similar products, but the retailer fought back and has more than 2,100 stores in 55 countries.
The family's statement said: "Gordon, Justine and Sam Roddick are very sad to announce that, after suffering a major brain haemorrhage, Anita Roddick died at 6.30pm this evening at the age of 64.
"Anita Roddick was admitted to St Richard's Hospital in Chichester, close to her home, yesterday evening when she collapsed after complaining of a sudden headache.
"Mrs Roddick was admitted to the hospital's intensive care unit and her husband Gordon and two daughters, Sam and Justine, were with her when she died."
Dame Anita revealed she was suffering from cirrhosis of the liver after contracting Hepatitis C from blood given during the birth of her youngest daughter, Sam.
She said she had unknowingly lived with "this silent killer" for three decades and only found out about it two years ago after a blood test.
"What I can say is that having Hep C means that I live with a sharp sense of my own mortality, which in many ways makes life more vivid and immediate," Dame Anita said.
"It makes me even more determined to just get on with things."
She told BBC News in July she had been having "some tiny heart attacks", which she put down to "getting in and out of aeroplanes so often".
"I can't really have any treatment because I have both cirrhosis and a particular strain of the virus that makes me unlikely to respond," she added.
Dame Anita started campaigning for Hepatitis C to be taken more seriously as a "public health challenge".
'Ahead of her time'
Justin Francis, who worked with her at Body Shop, said she was a "pioneer" who advocated business could be a "force for good".
He said: "She had a great passion for life, a great passion for business and for people. She was very warm, very witty and very clever."
John Sauven, executive director of Greenpeace, said Dame Anita was an "incredible woman" who was passionate about environmental and human rights issues.
He said: "She was an amazing inspiration to those around her.
"She was so ahead of her time when it came to issues of how business could be done...When you look at it today, and how every company claims to be green, she was living this decades ago."
Clive Stafford Smith, legal director of anti-death penalty organisation Reprieve, said she had just agreed to be its chairwoman.
"It is a real shame," he said. "We were so happy to have her, she was so full of life, so fantastic.
"She was so dedicated, so energetic, she will be sorely missed."
Emma Colyer from the HIV and Aids charity Body and Soul, which Dame Anita set up, told BBC News it was a terribly sad day for society at large.
"Anita carried out campaigns on so many issues and often issues that were not popular by the mass of public and took some strength of character to become involved in," she said.
Amnesty International UK director Kate Allen said Dame Anita's passion for human rights was "immeasurable".
She said: "We have lost a true champion of the oppressed and persecuted.
"Anita had been a key part of Amnesty International for many years and had shared her brilliance and energy with us to marvellous effect."