The US country and rock artist, who was also a well-regarded session guitarist for bands such as The Beach Boys, had been suffering from Alzheimer’s.
A family statement on the singer’s website read: “It is with the heaviest of hearts that we announce the passing of our beloved husband, father, grandfather, and legendary singer and guitarist, Glen Travis Campbell, at the age of 81, following his long and courageous battle with Alzheimer’s disease.”
The musician is survived by his wife Kim and their three children Cal, Shannon and Ashley.
He also had five children – Debby, Kelli, Travis, Kane and Dillon – from his three previous marriages.
Campbell was a grandfather, great-grandfather and great-great-grandfather.
His daughter Ashley, also a musician, posted a picture of her holding hands with her father on Twitter, writing: “Heartbroken. I owe him everything I am, and everything I ever will be.
“He will be remembered so well and with so much love.”
Campbell’s fellow country music star Dolly Parton said: “Glen is one of the greatest voices there ever was in the business and he was one of the greatest musicians.
“He was a wonderful session musician as well. A lot of people don’t realise that. But he could play anything and he could play it really well.”
Glen Campbell was one of the greatest voices of all time. I will always love you, Glen! pic.twitter.com/LQFEWA42lF
— Dolly Parton (@DollyParton) August 8, 2017
Campbell’s 1968 track Wichita Lineman was a worldwide hit, reaching No 1 in the US and No 7 in the UK.
Rhinestone Cowboy, in 1975, had similar levels of success around the globe, and went to No 4 in the British charts.
In total, Campbell had 10 top 40 hits in the UK and 15 studio, live or compilation LPs in the top 100 album charts.
As one of a group of 1960s musicians called The Wrecking Crew, he played on recordings by Bobby Darin, Dean Martin, Nat King Cole, The Monkees, Nancy Sinatra, Frank Sinatra, Elvis Presley and Phil Spector.
Because of his work on The Beach Boys’ classics like Help Me Rhonda and I Get Around, he regularly filled in for singer Brian Wilson when the group toured.
Campbell won 10 Grammy awards, including album of the year in 1968 for By The Time I Get To Phoenix, as well as a lifetime achievement award.
He also won numerous Academy of Country Music awards and, in 2007, was inducted into the Musicians Hall of Fame for his work as a member of The Wrecking Crew.
Campbell was also a successful actor, appearing in 1969 film True Grit alongside John Wayne.
He had publicly announced that he was suffering from Alzheimer’s in June 2011 – and then embarked on a nationwide farewell tour that ended in November 2012.
Campbell released his final studio album, called Adios, two months ago.