Singer and TV star Cilla Black, who enjoyed a 50-year showbusiness career, has died aged 72, her agent has said.
The 1960s singing star became a popular TV celebrity on such shows as Blind Date and Surprise Surprise.
Spanish police said a woman named Priscilla White - Black's real name - had died in Estepona on the Costa del Sol, where the star had a home.
The death appeared to be due to natural causes, but this had not yet been confirmed by tests, police said.
"It is with deep sorrow that I confirm... the passing of singer and TV personality Cilla Black," said her agent, Nick Fiveash.
"Details of her death will be announced following the coroner's report. Her family have asked for their privacy to be respected at this time."
Prime Minister David Cameron has paid tribute to the entertainer, remembering her as "a huge talent who made a significant contribution to public life".
Tributes have also been paid by her friends from the world of entertainment.
"I am so sad and shocked by news about my good friend Cilla," tweeted Dame Joan Collins. "She was a resplendent and rare talent."
"Such a shock to hear about Cilla's passing," said Sir Paul McCartney. "She was a lovely girl who infected everyone with her great spirit.
"From first meeting her as a cloak room girl at the Cavern in Liverpool, to seeing her many times since, she always had a fun-loving dignity that made her a great pleasure to be around."
Sir Bruce Forsyth said Black would be "sadly missed", while presenter Christopher Biggins described her as a "national treasure".
Broadcaster Noel Edmonds told BBC Radio 5 live she "captured the hearts of the British people" because "she was our Cilla - there were no airs and graces".
Songwriter Burt Bacharach, who worked with Black, said: "It will always be a most special memory for me of recording her on Alfie in Abbey Road Studios in 1965."
Des O'Connor called her "a very special lady", while broadcaster Gloria Hunniford - who saw Black two weeks ago at a friend's barbeque - called her "a true icon".
Dale Winton said Black had been "a dear and close friend" and "the most loyal person", as well as a "true 'star' and genuine national icon".
Lizo Mzimba, BBC entertainment correspondent
The phrase "national treasure" is often overused. But Cilla Black was one of the small group of entertainers who genuinely deserved it.
Long before she became a presenter she had an extraordinarily successful music career, with a string of top 10 hits.
She then did what few have managed and became equally successful in another arena, as a TV star.
Her easy going, natural manner endeared her to people, whom she famously addressed as "chuck".
And that unaffected charm was the reason millions of viewers welcomed her into their homes in shows like Surprise Surprise and Blind Date.
But it wasn't just audiences who loved her.
She also had the admiration and respect of fellow entertainers, some of whom had known her in Liverpool when she was still the teenaged Priscilla White.
Despite her success over the decades, she remained in many ways the same person to them - hard-working and passionate about performing.
That's what made her such a remarkable star.
Born Priscilla White in Liverpool, Black changed her name to launch a singing career with hits such as Anyone Who Had a Heart and You're My World.
Her career focus shifted to television in 1968, when she was given her own BBC One primetime series, and she went on to host a number of shows for ITV.
Black's journey to stardom began at Liverpool's famous Cavern Club, where she started work as a part-time cloakroom attendant.
It was there she met her husband-to-be Bobby Willis and went on to perform alongside such acts as The Beatles and Gerry and the Pacemakers.
She was soon brought to the attention of manager Brian Epstein and released her first single, Love of the Loved, in September 1963.
The following year she released the ballads You're My World and Anyone Who Had a Heart, both of which went to number one.
Cilla's hits in music and on television
She and Willis wed in 1969 and remained married until his death in 1999 at the age of 57.
The couple had three sons, one of whom, Robert, succeeded his father as her manager.
Last year Black received honours from Bafta and the Royal Television Society in recognition of her lengthy career.
A recent ITV drama series about her early years saw her played by the actress Sheridan Smith.
Gordon Burns, with whom Black worked on Surprise Surprise, told the BBC she was a "larger-than-life figure" and "a lorra lorra laughs" - a reference to one of her famous catchphrases.
Lord Grade, former executive chairman of ITV, said Black was a "natural performer of the highest quality" and "one of the all-time greats in showbiz".
The Cavern Club in Liverpool paid its own tribute with a sign announcing the death of its "famous cloak room girl".
Black was photographed by a fan at Gatwick Airport on Friday, shortly before she flew to Spain.
Amy Kelly said: "She looked so glamorous but frail. Everyone was talking about her but no one was asking for pictures.
"I said all of my family loved her and took a picture with her. She gave me a massive smile. She was so lovely."
Speaking to the BBC last year, Black described herself as "a lady of leisure" who was "living disgracefully" in semi-retirement.
"I'm going to enjoy myself," she told entertainment reporter Natalie Jamieson. "If it be in television then so be it, but I've had my time."