Queen Elizabeth II, 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.
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, Buckingham Palace said, "The Queen died peacefully at Balmoral this afternoon.
"The King and the Queen Consort will remain at Balmoral this evening and will return to London tomorrow."
All the Queen's children travelled to Balmoral, near Aberdeen, after doctors placed the Queen under medical supervision.
Her grandson, Prince William, is also there, with his brother, Prince Harry, on his way.

The Barber Academy Celebrates Ten Years
The International Salisbury Pancake Race Returns for 2026
Bishop of Salisbury to Commission Eight Volunteer Chaplains for the LGBTQIA+ Community
Tri-County Summit Boosts Joint Effort to Tackle Rural Crime
Local Voices Reveal Gaps and Solutions in Dementia Support
Rock and Roll Man Interviews: Part 3 - Julian Bird & Gary Turner
The Spitfire Café Brings Family Fun to Cross Keys This February Half Term
Local RNLI branch seeks more volunteers
