Justin Trudeau has expressed his condolences over the death of Queen Elizabeth II, telling reporters that that monarch, who was also Canada's head of state, was "one of my favourite people in the world".
"In a complicated world, her steady grace and resolve brought comfort and strength to us all. Canada is in mourning," said Trudeau, who first met the Queen as a child when his father Pierre was prime minister.
After Buckingham Palace announced the Queen had died at 96, tributes poured in from Canadian officials.
But her death is also likely to prompt fresh questions over the role of the monarchy in today's Canada, where support for the institution has dropped steadily in recent years.
"Canadians across the country will mourn the loss of the Queen. Let us take a moment to honour Her Majesty's memory in each of our own ways," said Mary Simon, the governor general, who represents the monarch in Canada.
"When I was growing up, my grandmother revered the Queen as did many in the Arctic. She would tell her stories about her Majesty, about her role and her commitment," Simon said in a later statement, alluding to her early life in the Canadian north.
As the first ever indigenous governor general, Simon has often reflected on the monarchy's role in Canada, its complicated relationship with colonialism - and the legacy that still holds for indigenous communities today.
Political leaders who have previously criticized the monarchy drew a sharp distinction for the late monarch, praising Elizabeth for her life of public service.
"Queen Elizabeth II lived a life of history and duty. She was also a mother, grandmother and great-grandmother," New Democratic party leader Jagmeet Singh wrote in a statement. "My thoughts today are for her family who have lost a pillar of strength in their lives."
The leader of the francophone separatist Bloc Quebecois extended condolences to Elizabeth's family and the UK.
"She will have been at the heart of a troubled century with the desire to be a positive force there," wrote Yves-François Blanchet.
In Ottawa, the Canadian flag atop parliament's Peace Tower was lowered to half-mast, as were flags at federal buildings across the country.
Following the news of the monarch's death, residents in the nation's capital began gathering outside Rideau Hall, the residence of the governor general, to pay tribute.
As head of state, Elizabeth II had a long connection to Canada. She also the first monarch to open a session of Canada's parliament in person, delivering the speech from the throne in 1957.
Twelve of Canada's 23 prime ministers have served under her. Over the years, she made 22 visits to Canada on royal tours, the first in 1951, when she was still a princess, and the most recent in 2010, where she visited five cities in nine days.
"My pride in the country remains undimmed," she told supporters in Halifax as she wrapped up her tour.
Governance in Canada is largely expected to carry on as usual, with the monarch remaining the constitutional head of state in Canada - no matter the individual in the role.
Related: Majority of Canadians think royal family 'no longer relevant'
In a citizenship swearing-in ceremony where new Canadians, up until hours ago, were required to swear allegiance to the Queen, the judge overseeing the event told attendees "the monarch is now King Charles III, King of Canada".
While the death of Elizabeth II will require a number of bureaucratic changes, it is also likely to renew scrutiny of the monarchy as a whole.
Precipitated in part by the tumultuous exit of Canada's governor general last year, recent polls found Canadians questioning the need for a constitutional monarchy. More than half of respondents believe the royal family is no longer relevant.
A royal as head of state for Canada is constitutionally entrenched, and any changes to the status quo would require constitutional changes assented to by the provinces.