Elizabeth II, Queen of the United Kingdom and the other Commonwealth realms, died on 8 September 2022 at Balmoral Castle in Scotland, at the age of 96. Elizabeth's reign of 70 years and 214 days was the longest of any British monarch. She was immediately succeeded by her eldest child, Charles III.

Elizabeth's death set in motion the final version of Operation London Bridge, a funeral plan first devised in the 1960s, and Operation Unicorn, the plan for the Queen's death in Scotland. Elizabeth's coffin lay at rest in St Giles' Cathedral in Edinburgh from 12 to 13 September, after which it was flown to London, where it lay in state in Westminster Hall from 14 to 19 September. An estimated 33,000 people filed past the Queen's coffin in Edinburgh, and approximately 250,000 people queued to pay their respects in London. The United Kingdom observed a national mourning period of 10 days.

Elizabeth's state funeral on 19 September was the first held in Britain since Winston Churchill's in 1965. A funeral service was held at Westminster Abbey, followed by a procession to Wellington Arch which featured around 3,000 military personnel and was watched by approximately one million people in central London. The state hearse then transported the Queen's coffin to Windsor, followed by another procession through Windsor Great Park and a committal service at St George's Chapel at Windsor Castle. The Queen was interred later that evening with her husband, Prince Philip, in the King George VI Memorial Chapel, in a private service attended only by her closest family.

Designated as a public holiday in the UK and several Commonwealth countries, the state funeral included dignitaries from around the world and featured the largest security operation ever mounted in the UK. Coverage of the state funeral was one of the UK's most watched special television broadcasts, surpassing the wedding of Prince William and Catherine Middleton, the previous most-watched royal event of the 21st century. The period of official mourning and the funeral was estimated to have cost the government £162 million.

Queen Elizabeth II was in good health for most of her life, but her health declined significantly following the death of her husband, Prince Philip, in April 2021. She began to use a walking stick for public engagements in October 2021. On 20 October, the Queen stayed overnight in King Edward VII's Hospital in central London, necessitating the cancellation of scheduled visits to Northern Ireland and the COP26 summit in Glasgow. She suffered a sprained back in November, which prevented her from attending the 2021 National Service of Remembrance.

In February 2022, during the COVID-19 pandemic in England, the Queen was one of several people at Windsor Castle to test positive for COVID-19. Her symptoms were described as "mild and cold-like", and she later commented that the disease "does leave one very tired and exhausted". The monarch's health became a cause of concern to commentators at this time.

The Queen was said to be feeling well enough to resume her official duties by 1 March 2022 and attended the service of thanksgiving for Prince Philip at Westminster Abbey on 29 March. Despite this, the Queen did not attend several appointments over the following months due to "episodic mobility problems", including the annual Commonwealth Day service in March, the Royal Maundy service in April, the State Opening of Parliament in May, and the National Service of Thanksgiving for her Platinum Jubilee in June. During the Jubilee the Queen also suffered "discomfort" after standing during Trooping the Colour and was largely confined to balcony appearances during the celebrations. According to her apothecary in Scotland, Douglas Glass, there had been private concerns about her health for several months before her death; he was quoted in a later biography as saying "It was expected and we were quite aware of what was going to happen."

Two days before her death, on 6 September 2022, the Queen accepted the resignation of Boris Johnson and appointed Liz Truss to succeed him as Prime Minister; these meetings took place at Balmoral Castle, rather than their usual location, Buckingham Palace. At the meeting with Truss, the final public photos of the Queen were taken by Jane Barlow. A bruise on her hand prompted public concern. Following the meeting the Queen's private secretary, Edward Young, privately informed Truss that the Queen might not live for much longer. He had also previously informed Johnson that regarding her health, the Queen had "gone down quite a bit over the summer" and later told him that the Queen knew she was dying throughout that summer. On 7 September, the Queen was scheduled to attend an online meeting of the Privy Council to swear in new ministers in Truss's government, but this was cancelled after she was advised by doctors to rest. The Queen's final public statement, issued that same day, was a message of condolences for the victims of a mass stabbing incident in Saskatchewan, Canada.