Royals, monarchs and crown princes from all over the world are expected for the state funeral, on what will undoubtedly be an enormously historic occasion.
But members of the royal houses of Europe will pay particularly poignant tributes, as many were close with the late monarch as friends and family.
Two generations of Spanish royalty will attend the funeral: current King Felipe VI and Queen Letizia, and Felipe's parents former King Juan Carlos and Queen Sofia.
King Felipe was Queen Elizabeth II's third cousin – and affectionately called her "Auntie Lilibet" –while his father King Juan Carlos is the great-great-grandson of Queen Victoria.
King Felipe VI and Queen Letizia
JUAN MEDINA
King Harald V and Queen Sonja of Norway
RITZAU SCANPIX
In a telegram sent to Buckingham Palace, King Felipe said her "sense of duty, commitment and lifetime of service to the people of the United Kingdom and Northern Ireland were an example to us all and will remain a strong and valuable legacy for future generations".
King Harald V and Queen Sonja of Norway will pay their respects in London.
Harald said in a statement: "For nearly a century, Her Majesty devoted her life to the service of the Commonwealth, following the British people through good days and bad, in times of happiness and sorrow."
He was Queen Elizabeth II's second cousin and shared the same great-grandparents – King Edward VII and Queen Alexandra.
The families were always close, not least because Harald's father and grandfather – King Haakon and Crown Prince Olav – lived in exile in London when Norway was occupied by Germany in World War 2.
It is said that Haakon was Queen Elizabeth II's favourite uncle and even that, given her nickname for him was "Uncle Charles" as a young girl, she named her first-born son after him.
Denmark's Queen Margrethe II, a third cousin of Queen Elizabeth II, will be attending the funeral.
In a letter to King Charles III, she said: "Your mother was very important to me and my family.
"She was a towering figure among European monarchs and a great inspiration to us all."
King Philippe and Queen Mathilde will be representing Belgium at the funeral on Monday.
Philippe is descended from Belgium's King Leopold I – Queen Victoria's uncle.
Following Queen Elizabeth II's death, the household released a message saying: "We will always keep fond memories of this great Lady who, throughout her reign, showed dignity, courage and devotion. Each of our encounters will remain etched in our memories forever."
Monaco's royal family will be represented at the funeral by Prince Albert II and Princess Charlene.
Writing to King Charles last week, Albert said: "Her Majesty’s unwavering commitment and dedication to duty during Her reign has always been extremely inspiring.
"It will be long remembered and admired.
"She truly represented the unity and dignity of the United Kingdom throughout the last seven decades."
Denmark's Queen Margrethe II
RITZAU SCANPIX
Dutch royals King Willem-Alexander and Queen Máxima join the Royal Family
Peter Nicholls
King Willem-Alexander and Queen Máxima will be attending the funeral in London on behalf of the Dutch royal family.
They said in a statement: "We remember Queen Elizabeth II with deep respect and great affection. Steadfast and wise, she dedicated her long life to serving the British people."
The Swedish royal family, represented by King Carl XVI Gustaf and Queen Silvia, will also be in attendance.
King Carl XVI Gustaf said in a statement: "She has always been dear to my family and a precious link in our shared family history."
He shared the same great-great-grandmother, Queen Victoria, with the late monarch.
