Born in the Egyptian city of Alexandria, al-Fayed began his career selling fizzy drinks and then worked as a sewing-machine salesman. He built his family's fortune in real estate, shipping and construction, first in the Middle East and then in Europe.
Although al-Fayed owned establishment symbols such as Harrods, Fulham and the Ritz hotel in Paris, he was always an outsider in Britain, tolerated but not embraced.
He fell out with the British government over its refusal to grant him citizenship of the country that was his home for decades, and often threatened to move to France, which gave him the Legion of Honour, its highest civilian award.
Al-Fayed - who could be charming, autocratic, vindictive, and at times wildly outspoken – spent 10 years trying to prove Diana and his son Dodi were murdered when their car crashed in a road tunnel in Paris in 1997 as they tried to outrun paparazzi photographers on motorbikes.
Unsupported by any evidence, according to the inquest into Diana's death, he claimed that she was bearing Dodi's child and accused Prince Philip, the queen's husband, of ordering Britain's security services to kill her to stop her marrying a Muslim and having his baby.
Al-Fayed died on Wednesday, his family said, a day before the 26th anniversary of Dodi and Diana's death.
"Mrs Mohamed Al Fayed, her children and grandchildren wish to confirm that her beloved husband, their father and their grandfather, Mohamed, has passed away peacefully of old age," the family statement read.
While al-Fayed was known for self-invention, exaggeration, and boasting, he was also a central figure in key moments in Britain's recent history.
His rancorous takeover of Harrods in 1985 sparked one of Britain's most bitter business feuds, while in 1994 he caused a scandal with the disclosure that he had paid politicians to ask questions on his behalf in parliament.
Like many billionaires, al-Fayed spurned convention. He once said he wanted to be mummified in a golden sarcophagus in a glass pyramid on the roof of Harrods.
At the store, where he instituted a dress code - even for customers - which he enforced in person, he installed a kitsch bronze memorial statue of Diana and Dodi dancing beneath the wings of an albatross.
As the owner of Fulham, he erected a larger-than-life, sequined statue of Michael Jackson outside the ground even though the singer only attended one match. When people complained, he said: "If some stupid fans don't understand or appreciate such a gift, they can go to hell."
HARRODS TAKEOVER
Much of al-Fayed's past remained murky - even his date of birth. He said he was born in then British-ruled Egypt in 1933. However, a British government inquiry into the Harrods takeover said 1929.
Al-Fayed became resident in Britain in 1974 and added the al to his name. Casting this as self-aggrandisement, the satirical magazine Private Eye nicknamed him the "Phoney Pharaoh".
In 1985 he and his brothers beat businessman Roland "Tiny" Rowland to Harrods, one of the most famous shops in the world.
Al-Fayed hoped that buying the store would win him acceptance in British society. Instead, it led to a series of bitter confrontations.
Rowland took al-Fayed and his brothers to a Department of Trade inquiry, claiming that they had misrepresented their wealth.
The inquiry cast doubt on their origins as part of a wealthy business family, past business connections, and their independent financial resources.
After a quarter of century of ownership, al-Fayed sold Harrods to Qatar's sovereign wealth fund in 2010.
Al-Fayed's application for British citizenship was denied by the government in 1995. He said racism kept him on the fringe of acceptability.
A year earlier, al-Fayed had embarrassed the government by disclosing that he had made gifts and payments to politicians in return for them asking parliamentary questions for him. The so-called "cash-for-questions" scandal ended the careers of four politicians, including one minister.
The allegations of sleaze undermined the Conservatives, who lost a landslide election to Labour leader Tony Blair in 1997.
DIANA AND DODI
That summer, al-Fayed's son Dodi began a relationship with Princess Diana, who had divorced Prince Charles, the heir to the British throne. Dodi and Diana were pictured by British tabloids on holiday on a yacht in the south of France.
Beset by grief and an overwhelming sense of injustice, al-Fayed spent millions on legal battles to ensure there was an inquest.
When it started in London a decade after the crash, al-Fayed would accuse everyone from the royal family, prime minister Blair, Diana's sister Sarah, the French embalmers of Diana's body, and the Paris ambulance drivers of being implicated.
But the jury said the couple were unlawfully killed by their chauffeur's driving. Al-Fayed said he accepted the verdict and gave up legal attempts to show they were murdered.
"I'm leaving the rest for God to get my revenge," he said.
