Denmark's Queen Margrethe II has announced her surprise abdication in a new year TV address.
She will abdicate the throne on 14 January, which will be 52 years to the day since she became queen.
Her eldest son Crown Prince Frederik will take the role of king following Margrethe's departure.
The 83-year-old is the longest serving monarch in Danish history, taking the throne after the death of her father King Frederik IX in 1952.
She revealed the decision was made after a period of reflection following surgery on her back in early 2023.
The surgery naturally gave rise to thinking about the future - whether the time had come to leave the responsibility to the next generation," she said.
"I have decided that now is the right time," she added, and offered her thanks to the Danish public for their support over the years.
Prime Minister Mette Frederiksen thanked the queen for her service.
"On behalf of the entire population, I would like to extend a heartfelt thank you to Her Majesty The Queen for her lifelong dedication and tireless efforts for the Kingdom," she said in a statement.
"Although the duty and position of regent has been handed down for more than 1,000 years, it is still difficult to understand that the time has now come for a change of throne," the statement read.
"Many of us have never known another regent. Queen Margrethe is the epitome of Denmark and throughout the years has put words and feelings into who we are as a people and as a nation."
Unlike British royal tradition, there will be no formal crowning ceremony for Crown Prince Frederik, who is 55. Instead, his accession will be announced from Amalienborg Castle in Copenhagen on the day.
He will take her place as King of Denmark and head of state in the country - which is a constitutional monarchy - as well as in Greenland and the Faroe Islands.
Queen Margrethe is a popular figure in Denmark, and many Danes had expected her to remain on the throne until her death.
"She is to us what Queen Elizabeth was to you," Danish journalist Tine Gotzsche told the BBC.
Queen Margrethe attended the funeral of Queen Elizabeth II in 2022, and they celebrated their respective jubilees in the same year.
She had not been expected to become Queen when she was born. But when she was 13, Danish law changed to allow women to take the throne.
More than a decade ago, Queen Margrethe reflected that she was inspired by the late British Queen "that I must somehow understand that I must dedicate my life to my nation like she has done, and in that way she has been very important to me."
The pair had been the world's only remaining female sovereigns before Queen Elizabeth's death.
"She has always been there, she has been ageing with all of us," she said, but added: "the Crown Prince is in a very good position to take over, the succession is laid out - it's very logical, and it absolutely makes sense."
Crown Prince Frederik, like Britain's King Charles III, is known for his passion for the environment. He has vowed to "guide the ship" of Denmark into the future.
His wife, Princess Mary, grew up on the Australian island of Tasmania and was working as a lawyer when the pair met in 2000.
They are considered by some to represent modern values and have tried to give their four children as normal an upbringing as possible, sending them mainly to state schools.
During her time on the throne, Queen Margrethe continued to work as an artist and was well known for her love of the arts.
She also has a passion for archaeology and has taken part in several excavations.
She studied in the UK, spending time at Cambridge's Girton College and the London School of Economics.
In 1967, she married French diplomat Henri de Laborde de Monpezat, who served as her royal consort until his death in 2018.
Each year on New Year's Eve, she delivers a speech broadcast on television.
This year, aside from the announcement, she also spoke of the wars in the Middle East and Ukraine, as well as the importance of addressing climate change.
Facing similar challenges of modern society as other royal families across Europe, the Danish royal family has decided to slim down its number of royals.
This led to a very public rift last year after Crown Prince Frederik's younger brother Prince Joachim's children were stripped of their royal titles.
Known for her smoking habits and rejection of mobile phones
Some also consider her the world's longest reigning monarch. The Sultan of Brunei has been on the throne for longer, but his country only gained independence in 1984.
She is also the longest-serving monarch in Danish history, after surpassing King Christian IV, of Denmark and Norway, earlier this year.
Affectionately known as Daisy, Queen Margrethe is known for her smoking habits and rejection of mobile phones and the internet - declaring herself "very happy" without them.
Gotzsche said the Danish royal transition is a moment of mixed celebration and sadness.
BBC