Brown was hospitalized with pneumonia at Emory Crawford Long Hospital on Sunday and died around 1:45 a.m. Monday, said his agent, Frank Copsidas of Intrigue Music. Longtime friend Charles Bobbit was by his side, he said.
Copsidas said the cause of death was uncertain. "We really don't know at this point what he died of," he said.
Along with Elvis Presley, Bob Dylan and a handful of others, Brown was one of the major musical influences of the past 50 years. At least one generation idolized him, and sometimes openly copied him. His rapid-footed dancing inspired Mick Jagger and Michael Jackson among others. Songs such as David Bowie's "Fame," Prince's "Kiss," George Clinton's "Atomic Dog" and Sly and the Family Stone's "Sing a Simple Song" were clearly based on Brown's rhythms and vocal style.
"James presented obviously the best grooves," rapper Chuck D of Public Enemy once told The Associated Press. "To this day, there has been no one near as funky. No one's coming even close."
His hit singles include such classics as "Out of Sight," "(Get Up I Feel Like Being a) Sex Machine," "I Got You (I Feel Good)" and "Say It Loud — I'm Black and I'm Proud," a landmark 1968 statement of racial pride.
"I clearly remember we were calling ourselves colored, and after the song, we were calling ourselves black," Brown said in a 2003 Associated Press interview. "The song showed even people to that day that lyrics and music and a song can change society."
He won a Grammy award for lifetime achievement in 1992, as well as Grammys in 1965 for "Papa's Got a Brand New Bag" (best R&B recording) and for "Living In America" in 1987 (best R&B vocal performance, male.) He was one of the initial artists inducted into the Rock and Roll Hall of Fame in 1986, along with Presley, Chuck Berry and other founding fathers.
He triumphed despite an often unhappy personal life. Brown, who lived in Beech Island near the Georgia line, spent more than two years in a South Carolina prison for aggravated assault and failing to stop for a police officer. After his release on in 1991, Brown said he wanted to "try to straighten out" rock music.
From the 1950s, when Brown had his first R&B hit, "Please, Please, Please" in 1956, through the mid-1970s, Brown went on a frenzy of cross-country tours, concerts and new songs. He earned the nickname "The Hardest Working Man in Show Business" and often tried to prove it to his fans, said Jay Ross, his lawyer of 15 years.
Brown would routinely lose two or three pounds each time he performed and kept his furious concert schedule in his later years even as he fought prostate cancer, Ross said.
"He'd always give it his all to give his fans the type of show they expected," he said.
With his tight pants, shimmering feet, eye makeup and outrageous hair, Brown set the stage for younger stars such as Michael Jackson and Prince.
In 1986, he was inducted in the Rock and Roll Hall of Fame. And rap stars of recent years overwhelmingly have borrowed his lyrics with a digital technique called sampling.
Brown's work has been replayed by the Fat Boys, Ice-T, Public Enemy and a host of other rappers. "The music out there is only as good as my last record," Brown joked in a 1989 interview with Rolling Stone magazine.