King George III was born on 4th June 1738 and on the death of his grandfather King George II on 25th October 1760, became King of Great Britain and King of Ireland.
On 1st January 1801 the crowns of Great Britain and Ireland were united and he became King of Great Britain and Ireland.
His reign ended with his death at the age of 81, on 29th January 1820, having lasted for 59 years and 96 days
No person - or country - has ever ruled "the world".
Certain empires (such as the Romans) have ruled large parts of what they knew to be the world at the time, but they still didn't rule all they knew of.
The longest reign in history was Pepi II of ancient Egypt, who ruled from childhood until his death, 94+ years, over 4,000 years ago.
Rameses
Fidel Castro 1959-2010 - 51 years
As of my last update, Bruno Sammartino holds the record for the longest single reign as a world champion in WWE history, with a reign lasting 2,803 days as the WWE Champion.
The longest presidential reign in Kenya was 24 years by Daniel Arap Moi.
As the longest reign in European history.
Bruno Sammartino has held the WWE Championship the longest, a whooping 2803 days (first reign) from May 17th, 1963 to January 18th, 1971!John Cena has the longest reign for the current WWE Roster with 380 days for his third WWE Championship reign between September 17,2006 and October 2,2007.
From April 3 2005 to January 10 2006 (282 Days)
Current Middleweight Champion Anderson Silva has the longest title reign in UFC history
Kane
yes
Czar Nichaols was descended from the roayl family of Romanovs. The Communists executed him and his entire family, thus ending the 200-year reign of the Romanov family in Russia---the longest reign of any family in Europe.