Hallyday was born in Paris to a Belgian father and French mother. As his parents soon divorced he was brought up by his aunt Hélène Mar. For many years Hallyday thought he possessed dual Belgian French nationality. His father had recognised him, but as he was still married to another woman under Belgian law at the time his father was legally unable to recognise him officially.
Honorary Belgian perhaps, as some years before his death he was awarded the medal of Grand Officer in the Order of the Crown, a major Belgian distinction and always insisted half his heart resided in Brussels. To this day Hallyday possessed an immense following in Belgium performing over fifty times at the Vorst Nationaal concert hall in Brussels. He also performed on stage at the King Boudewijn Stadium.
French President Emmanuel Macron announced the Belgo-French singer’s death in a statement early Wednesday, saying "he brought a part of America into our national pantheon." Macron's office said the president spoke with Hallyday's family but did not provide details about where the rocker died or the circumstances.
Hallyday had had lung cancer and repeated health scares in recent years that dominated national news, yet he continued performing as recently as this summer.
Celine Dion was among stars sharing condolences for a rocker with a famously gravelly voice who sold more than 100 million records, filled concert halls and split his time between Los Angeles and Paris.
Hallyday fashioned his glitzy stage aura from Elvis Presley, drew musical inspiration from Chuck Berry and Buddy Holly, performed with Jimi Hendrix, and made an album in country music's capital, Nashville, Tennessee.
His stardom largely ended at the French-speaking world, yet in France and Belgium, he was an institution, with a postage stamp in his honour. He was the France's top rock 'n' roll star through more than five decades and eight French presidents and even more Belgian premiers, and it was no exaggeration when Macron wrote "the whole country is in mourning."
"We all have something of Johnny Hallyday in us," Macron said, praising "a sincerity and authenticity that kept alive the flame that he ignited in the public's heart."
The antithesis of a French hero right down to his Elvis-style glitter and un-French name, Hallyday was among the most familiar faces and voices in France, which knew him simply as Johnny, pronounced with a slight French accent and beloved across generations.
He released his last album "Rester Vivant" — or "Staying Alive" — last year, and performed this summer as part of the "Old Crooks" tour with long-time friends and veteran French musicians Eddy Mitchell and Jacques Dutronc.
Former President Nicolas Sarkozy, as mayor of the rich enclave of Neuilly-sur-Seine on the western edge of Paris, presided in 1996 over the entertainer's marriage to his fourth wife, Laeticia.
"For each of us, he means something personal. Memories, happy moments, songs and music," Sarkozy said in 2009, days after Hallyday, then 66, was hospitalized in Los Angeles. Sarkozy called the Hallyday family during an EU summit and gave updates on the singer's condition during news conferences.
The health problems came amid a national tour that included a Bastille Day mega-concert July 14 at the Eiffel Tower with spectacular fireworks.
Hallyday sang some songs in English, including "Hot Legs" and "House of the Rising Sun," — the melody of which was also used for one of his most famous songs, the 1964 "Le Penitencier."
And there was a real American connection: American singer Lee Ketchman gave him his first electric guitar. Hallyday's stardom, however, was not inevitable.
He was born in Paris on June 15, 1943, during the dark days of World War II with a less glamorous name, Jean-Philippe Smet. His parents had separated by the end of the year. The young Smet followed his father's sisters to London, where he met Ketchman.
Hallyday gave his first professional concert in 1960, under the name Johnny, and put out his first album a year later. By 1962, he had met the woman who would be his wife for years, and remained his friend to the end, singing star Sylvie Vartan. That year, he also made an album in Nashville, Tennessee, and rubbed shoulders with American singing greats.
He quickly became a favourite of young people during the "Ye-ye" period, the golden years of French pop music. A respected musician, Hallyday played with Jimmy Hendrix during the 1960s and once recorded a song with Led Zeppelin founder Jimmy Page.
With his square-jawed good looks and piercing blue eyes, Hallyday was often sought-out for the cinema, playing in French director Jean-Luc Godard's "Detective" (1984) and with other illustrious directors including Costa-Gavras.
Hallyday appeared in Johnnie To's "Vengeance" (2009) and had talked about giving film a bigger role in his life.
However, it was the rocker's personal life, and his marriage to Laeticia, that gave him a mellow edge. He spoke lovingly of daughters Jade and Joy, who were adopted from Vietnam.
"I'm not a star. I'm just a simple man," he said in a 2006 interview on France 3.
Hallyday is also survived by two other children, Dave, a singer fathered with Vartan, and Laura Smet, whom he had with noted French actress Nathalie Baye.
Memorial plans weren't immediately announced.