Queen Elizabeth, the UK's longest-serving monarch, has died at Balmoral aged 96, after reigning for 70 years.
Her family gathered at her Scottish estate after concerns grew about her health earlier on Thursday.
The Queen came to the throne in 1952 and witnessed enormous social change.
Ratu Epeli Nailatikau, back, during Queen Elizabeth II and Prince Philip’s visit to Fiji in 1977. Photo: Supplied
With her death, her eldest son Charles, the former Prince of Wales, will lead the country in mourning as the new King and head of state for 14 Commonwealth realms.
In a statement, The King said: "The death of my beloved mother Her Majesty The Queen, is a moment of the greatest sadness for me and all members of my family.
"We mourn profoundly the passing of a cherished Sovereign and a much-loved Mother. I know her loss will be deeply felt throughout the country, the Realms and the Commonwealth, and by countless people around the world."
All the Queen's children travelled to Balmoral, near Aberdeen, after doctors placed the Queen under medical supervision.
Queen Elizabeth's tenure as head of state spanned post-war austerity, the transition from empire to Commonwealth, the end of the Cold War and the UK's entry into - and withdrawal from - the European Union.
Her reign spanned 15 prime ministers starting with Winston Churchill, born in 1874, and including Liz Truss, born 101 years later in 1975, and appointed by the Queen earlier this week.
Fiji PM Bainimarama has tweeted this morning: "Fijian hearts are heavy this morning as we bid farewell to Her Majesty Queen Elizabeth II. We will always treasure the joy of her visits to Fiji along with every moment that her grace, courage, and wisdom were a comfort and inspiration to our people, even a world away."
Queen's many visits to the Pacific
The Queen visited the Pacific multiple times during her reign, with a visit a few months after her coronation to Fiji and Tonga, in December 1953.
She attended the opening of the Rarotonga International Airport in 1974.
In October 1982, her tour included Papua New Guinea, Solomon Islands, Nauru, Kiribati, Tuvalu and Fiji.
Together with her husband, Prince Philip, the Queen visited Fiji on February 16-17, 1977, as part of the Silver Jubilee Celebrations of her accession to the British throne.
Fiji media had reported that during a banquet dinner held in her honour in Suva, the Queen told the 300 guests present Fiji was the first Pacific country she had seen in 1953.
The Queen visited Fiji six times during her reign.
Queen Elizabeth II Photo: Getty Images / Bettmann
Matangi Tonga reported Queen Elizabeth had a special relationship with Tonga and Tonga's Royal Family after Queen Sālote Tupou III attended her coronation in London.
In 1953 Queen Elizabeth made a special visit to Tonga. She laid a wreath at the cenotaph in Pangai Si'i, a small park that Queen Sālote had developed (now the site of the St George Government Building) and attended a feast at the Royal Palace in Nuku'alofa.
At the time of the Queen's 70th jubilee, British High Commissioner to the Kingdom of Tonga, Lucy Joyce, wrote that Queen Elizabeth's links to Tonga went back to her coronation.
She visited the Kingdom three times: in December 1953, in March 1970 when the couple were accompanied by Princess Anne; and during the Silver Jubilee year of 1977.
The UK was also on hand to provide assistance after the volcano and tsunami in February.
Joyce wrote it was a clear recent example of the solidarity between Commonwealth nations.