This is what we found on Wikipedia regarding the Ranulph Fiennes:

Sir Ranulph Twisleton-Wykeham-Fiennes, 3rd Baronet (born 7 March 1944), commonly known as Sir Ranulph Fiennes () and sometimes as Ran Fiennes, is a British explorer, writer and poet, who holds several endurance records.

Fiennes served in the British Army for eight years, including a period on counter-insurgency service while attached to the Army of the Sultanate of Oman. He later undertook numerous expeditions and was the first person to visit both the North Pole and South Pole by surface means and the first to completely cross Antarctica on foot. In May 2009, at the age of 65, he reached the summit of Mount Everest.

According to the Guinness Book of World Records in 1984, he was the world's greatest living explorer. Fiennes has written numerous books about his army service and his expeditions as well as books on explorers Robert Falcon Scott and Ernest Shackleton.