Reports from Tonga say the Pacific island nation's King George Tupou the 5th has died in a Hong Kong hospital.
The local media say the 63-year-old monarch passed away late Sunday, with his younger brother and heir to the throne, Crown Prince Tupouto'a Lavaka, at his side.
King Tupou, known to the outside world for eccentricities such as being driven around in a London taxi, will be remembered by his subjects for introducing democracy to the nation of 100,000 people. He was sworn in as king in September 2006 following the death of his father, King Taufa'ahau Tupou the 4th.
In November 2010, the Polynesian nation held its first direct elections, which marked the end of centuries of monarchic rule in Tonga. In December, the newly elected parliament confirmed Lord Tu'ivakano as the country's first elected prime minister.
Previous prime ministers were appointed by the king.