This article was first published on Sept 9, 2015, and was updated on Oct 14, 2016.
The world's longest-reigning monarch, Thailand's King Bhumibol Adulyadej, died in hospital on Thursday (Oct 13), the palace said in an announcement. He was 88 and had marked the 70th year of his reign in June.
The death of King Bhumibol means Queen Elizabeth II of Britain and the Commonwealth Realms becomes the world's longest reigning monarch.
The following is a list of the current longest-reigning heads of state:
BRITAIN (Queen Elizabeth II, 64 years)
Queen Elizabeth II, born on April 21, 1926, inherited the throne on Feb 6, 1952, following the death of her father, King George VI.
On Sept 9, 2015, Queen Elizabeth's reign surpassed that of Queen Victoria, who was on the throne from 1837 until 1901, a total of 63 years, seven months and two days. Queen Elizabeth is queen of 15 other Commonwealth realms.
BRUNEI (Sultan Hassanal Bolkiah, 49 years)
Sultan Hassanal Bolkiah, 69, is one of the richest people on the planet. He has reigned over the small enclave on the north coast of Borneo since his father abdicated in October 1967. Brunei has sizeable petroleum reserves.
OMAN (Sultan Qaboos, 36 years)
Sultan Qaboos, 74, took the throne on July 23, 1970, after ousting his father for allegedly being too conservative. The Sultan has set about reforming the small sultanate, which controls the strategic Strait of Hormuz along with Iran, but his health is failing and he has no designated heir.
DENMARK (Queen Margrethe II, 34 years)
Queen Margrethe II, 75, became head of Europe's oldest kingdom on Jan 14, 1972, following the death of her father, Frederik IX.
SWEDEN (King Carl XVI Gustaf, 33 years)
King Carl XVI Gustaf, 69, succeeded his grandfather, Gustaf VI Adolf, in September 1973. He and Queen Margrethe are first cousins.
The late King Bhumibol holds the modern record for longevity on the throne with a reign of 70 years.
Before King Bhumibol, the modern record for longevity was held by Japanese Emperor Hirohito, who died in January 1989 at the age of 87 after reigning for 62 years.
In Europe, the longest verified reign is that of French King Louis XIV (72 years between 1643 and 1715). Austrian emperor Franz Joseph I reigned for nearly 68 years between 1848 and 1916.
SOURCE: AGENCE FRANCE-PRESSE, BBC