Denmark’s Prince Henrik, controversial husband of Queen Margrethe, has died at Fredensborg Castle, the royal house said in a statement.
He was 83 and had been diagnosed with a benign tumour two weeks ago.
"His Royal Highness Prince Henrik died peacefully in his sleep," the royal house said. "Her Majesty the Queen and the two sons were at his side."
The French-born prince, who had been hospitalised following an illness that began during a private trip to Egypt, died last night.
Shortly before his death, he was transferred from a Copenhagen hospital back to the castle, north of the city, where he had wanted to spend "his final time".
Prince Henrik sparked controversy in August 2017 when he announced he did not wish to be buried next to the Queen, breaking a 459-year tradition.
He said he was unhappy she had never acknowledged him as her equal.
Shortly after, the palace announced that Prince Henrik was suffering from dementia.
He formerly held the title of prince consort but renounced that title when he retired from his official duties in 2016.
He had often spoken of his frustration at being denied the title of king instead of prince consort.
In Denmark, a princess traditionally becomes queen when her husband takes the throne, but a man does not become king when the roles are reversed.
After a 2009 Danish referendum supported the equality of the sexes in the royal succession, Prince Henrik remarked: "I hope that men will be as equal as girls," spurring further debate and briefly finding support in parliament in favour of allowing the queen's husband the title of king.
Both loved and criticised by the Danes for his aristocratic manner, best exemplified by his colourful clothes and thick French accent, in recent years Prince Henrik found support particularly amongst the Danish youth for breaking with the Danish norms of cultural uniformity.
In 2016, he renounced his title of Prince Consort and retired from his official duties. Thereafter, he spent much of his time at his private vineyard in Château de Cayx, France, although he remained married to the queen and was officially still living with her.
Known for his love of wine and food, the prince was also a passionate artist, producing sculptures, poems and cookery books.
Born Henri Marie Jean André de Laborde de Monpezat in France in 1934, he married Margrethe in 1967.
Prince Henrik has two sons with the queen, Crown Prince Frederik and Prince Joachim.