Phil Everly - who with his brother, Don, made up the revered US rock and country duo - has died aged 74.
He passed away in the Los Angeles suburb of Burbank following complications from chronic obstructive pulmonary disease, his wife, Patti, told the LA Times.
His wife told the newspaper that the disease was contracted through a lifetime of smoking and that the family was "absolutely heartbroken".
The Everly Brothers, with their high, close-harmony singing, had 19 top 40 hits during their heyday between 1957 and 1962.
Their songs include Bye Bye Love, All I Have To Do Is Dream, Cathy's Clown, and Wake Up Little Susie.
They profoundly influenced 1960s-era groups and singer-songwriters ranging from Beatles John Lennon and Paul McCartney, who early in their careers called themselves the Foreverly Brothers, to Simon and Garfunkel, the Byrds, the Hollies and the Beach Boys.
"Perhaps even more powerfully than Elvis Presley, the Everly Brothers melded country with the emerging sound of Fifties rock & roll," Rolling Stone magazine said in placing the brothers at No.33 on its list of the 100 Greatest Artists.
Tributes have poured in for the youngest of the duo.
Rock and country singer-songwriter Charlie Daniels tweeted: "Rest in peace Phil Everly. You guys brought us a lot of pleasure back in the day."
Linda Ronstadt, who recorded one of the biggest hits of her career in 1975 with her interpretation of the Everlys' When Will I Be Loved, said: "They had that sibling sound. The information of your DNA is carried in your voice, and you can get a sound (with family) that you never get with someone who's not blood-related to you.
"And they were both such good singers -- they were one of the foundations, one of the cornerstones of the new rock 'n' roll sound."
Phil in London in 1974 Don was born in 1937 in Brownie, Kentucky, to Ike and Margaret Everly, who were folk and country music singers.
Phil was born to the couple on January 19, 1939, in Chicago where the Everlys moved to from Brownie when Ike grew tired of working in coal mines.
The brothers began singing country music in 1945 on their family's radio show in Shenandoah, Iowa.
Their career breakthrough came when they moved to Nashville in the mid-1950s and signed a recording contract with New York-based Cadence Records.
In all, their career spanned five decades, although they performed separately from 1973 to 1983 after a dramatic onstage break-up during a concert in California.
Phil threw his guitar down and walked off, prompting Don to tell the crowd: "The Everly Brothers died 10 years ago."
During their breakup, they pursued solo singing careers with little fanfare. Phil also appeared in the Clint Eastwood movie Every Which Way But Loose.
After their decade-long estrangement, the brothers reunited in 1983 - "sealing it with a hug," Phil said at the time.
They were inducted into the Rock 'n' Roll Hall of Fame in 1986, the same year they had a hit pop-country record, Born Yesterday.
Speaking in an interview in 1986, Don said the duo were successful because "we never followed trends".
He added: "We did what we liked and followed our instincts. Rock 'n' roll did survive, and we were right about that. Country did survive, and we were right about that. You can mix the two but people said we couldn't."
Phil is survived by Don, wife Patti, mother Margaret, sons Jason and Chris, and two granddaughters.
:: Watch Sky News live on television, on Sky channel 501, Virgin Media channel 602, Freeview channel 82 and Freesat channel 202.
Barmouth sea front in west Wales also suffered extensive damage
The worst affected area is the Severn Estuary
Harry Martin has not been seen since Thursday
The south of England is still subject to dozens of flood warnings
Weather watchers risk a soaking at Westward Ho!, Devon. Pic: Chris Wileman
River Severn levels are reaching historic highs at Epney, Gloucestershire
A canoeist on Worcester racecourse. Pic by Dave Key
Parts of Gloucestershire are underwater after the Severn's banks broke
Sinn Fein President Gerry Adams says an agreement has not been reached
Ruth Jones gets a CBE
Michael Crawford picks up a CBE
The death toll could rise further
Security has been stepped up after the station blast
Michael Schumacher was skiing with his son at the time of the accident
The racer was taken to hospital by helicopter
Doctors could not give a prognosis at a press conference in Grenoble
The German Formula One legend skiing in Italy in 2006
The accident occurred in the resort of Meribel in France
Schumacher made a comeback to Formula One for Mercedes in 2010
More than one in five adults in the UK admit to smoking
The ferry was forced to loop back when it was 30 miles off Flamborough Head
This photo of the RAF helicopter was taken by a passenger
Passengers were kept on board until 9am on Sunday while police investigated
Police arrived at the Newcastle Ferry Port in the early hours
Firefighters at the scene