Glen Campbell, the indelible voice behind 21 Top 40 hits including “Rhinestone Cowboy,” “Wichita Lineman” and “By the Time I Get to Phoenix,” died Tuesday. He was 81.

A rep for Universal Music Group, Campbell’s record label, confirmed the singer’s death to Rolling Stone. During a career that spanned six decades, Campbell sold over 45 million records. In 1968, one of his biggest years, he outsold the Beatles.

“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 singer’s family said in a statement.

Campbell was a rare breed in the music business, with various careers as a top-level studio guitarist, chart-topping singer and hit television host. His late-career battle with Alzheimer’s – he allowed a documentary crew to film on his final tour for the 2014 award-winning I’ll Be Me – made him a public face for the disease, a role President Bill Clinton suggested would one day be remembered even more than his music.

“He had that beautiful tenor with a crystal-clear guitar sound, playing lines that were so inventive,” Tom Petty told Rolling Stone during a 2011 profile of Campbell. “It moved me.”

Campbell was born in 1936 in Billstown, Arkansas, the seventh son in a sharecropping family of 12 kids. “We used to watch TV by candlelight,” Campbell told Rolling Stone in 2011.

In his youth, Campbell started playing guitar and became obsessed with jazz guitarist Django Reinhardt. He dropped out of school when he was 14 and moved to Wyoming with an uncle who was a musician, playing gigs together at rural bars. He soon moved to Los Angeles and by 1962 had solidified a spot in the Wrecking Crew, a group of session pros. In 1963 alone, he appeared on 586 cuts and countless more throughout the decade, including the Byrds’ “Mr. Tambourine Man,” Elvis Presley’s “Viva Las Vegas,” Merle Haggard’s “Mama Tried” and the Righteous Brothers’ “You’ve Lost That Lovin’ Feeling.”

Campbell was married four times, and has five sons and three daughters. In the early 1980s, while battling alcoholism and cocaine addiction, Campbell made tabloid headlines with a 15-month, high-profile relationship with country singer Tanya Tucker, who was 22 years his junior. In 1981, he became a born-again Christian and in 1982 he married Kimberly Woollen, a Radio City Music Hall Rockette, who helped Campbell clean up his life.

He spent his final years in an assisted living facility. His friends and children would often spend days with him playing him his old songs. “Music utilizes all of the brain, not just one little section of it,” Woollen noted. “Everything’s firing all at once. It’s really stimulating and probably helped him plateau and not progress as quickly as he might have. I could tell from his spirits that it was good for him. It made him really happy. It was good for the whole family to continue touring and to just keep living our lives. And we hope it encourages other people to do the same.”

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