A direct descendant of Emperor Charlemagne and a cousin of actor Ralph Fiennes, he has marched around the globe from astonishing challenge to astonishing challenge throughout his adult life, earning a reputation as the world's greatest living explorer.
That title was bestowed on him by the Guinness Book of Records and Sir Ranulph's achievements appear to justify it.
Educated at Eton, the 55-year-old gave early indications of his adventurous spirit. He followed his late father's footsteps into the army before switching to the elite SAS regiment, where he became the youngest captain in the British army. He was dismissed following a prank in which he blew up the set of the movie Doctor Doolittle and moved to the Middle East as a member of the Sultan of Oman's forces.
But adventure beckoned and, after two years, he launched himself into a series of expeditions.
He went up the White Nile in a hovercraft in 1969, led an expedition into Jostedalsbre Glacier in 1970 and led another into British Columbia's Headless Valley in 1971.
In 1979, Sir Ranulph undertook possibly his most extraordinary adventure.
For three years, he and his team undertook a transglobal expedition, the first surface circumpolar trip around the world. The team travelled 160,000 kilometres.
They crossed the mighty Sahara, struggled through the swamps and jungles of Mali and Ivory Coast, mastered the unpredictable Arctic Ocean, crossed the crevasse-ridden Antarctic and negotiated the unfriendly Northwest Passage.
Sir Ranulph has long been fascinated by the legends of the Lost City of Ubar, which Lawrence of Arabia described as the Atlantis of the Sands, and he was determined to find it. It took several expeditions in the vast deserts of Arabia before he found the city in Oman in 1992.
The following year, Sir Ranulph and Dr. Mike Stroud became the first to cross the Antarctic continent unassisted. The two men, fighting snow blindness, dragged 225-kilogram sleds for 97 days to complete the trip.
It was in this year that Sir Ranulph, who had inherited his knighthood, was awarded the Order of the British Empire for "human endeavour and charitable services." To date, his expeditions have raised more than $12 million for charity.
While not exploring, Sir Ranulph writes books from his home in West Somerset, England. He has 12 titles to his name, including The Sett, published in 1996, From Pole to Pole in 1998 and Fit for Life last year.
He even finds time to pack in speaking engagements all over the world. He has been an IBM choice as its chief motivational speaker from a field of 700 international names and Britain's Daily Telegraph lists him as one of the top 20 international speakers.
Sir Ranulph has a host of admirers, including Prince Charles, the patron of his circumpolar expedition, who describes him as: "Mad but marvellous."
"My admiration for Ran is unbounded and thank God he exists," Prince Charles has said. "The world would be a far duller place without him."