The cause of Hayes' death was not immediately known
Stars including Dionne Warwick and Aretha Franklin have paid tribute to the soul legend Isaac Hayes, who has died at his home in Memphis aged 65.
"I've lost one of my best buddies and it is not easy to reckon with," Warwick told US TV show Access Hollywood.
Franklin told MTV that Hayes was "an enduring symbol of the struggle of the African-American man and was a shining example of soul at its best".
He was taken to hospital after he was found unconscious next to a treadmill.
Franklin said Hayes was "so musically advanced and timeless in his compositions". She added: "He was loved and appreciated by so many."
Gloria Gaynor called him "a gentleman and an extremely warm and talented artist", who she "respected and admired".
In 1985 Gaynor recorded one of Barry White's songs, You're The First, The Last, My Everything, for Hayes.
"I will miss him and his contribution to the entertainment world and to human kind," she said.
Hayes started his career as a songwriter for the legendary Stax label, penning hits including Soul Man and Hold On I'm Coming for duo Sam and Dave.
Sam Moore told BBC 6 Music he was "just the most, sensitive nicest kind" man.
"Isaac is now free," he said. "He is at peace. No-one can hurt him any longer. No-one can use him. He doesn't have to work."
Portishead sampled Hayes' Ike's Rap on their breakthrough single Glory Box in 1994.
Speaking to BBC News, the band's Adrian Utley said: "It was just cool as hell. We had Isaac Hayes records hanging around. It's purely sonic, it sounded so good. It was just immediately a very cool track.
"I would say we've definitely got him to thank, because had he not written that tune we wouldn't have sampled it and the basis of the music that you hear is his."
Hayes, a flamboyant, deep-voiced performer, won an Oscar for the 1971 hit Theme From Shaft.
He was perhaps better known to a younger audience as the voice of Chef from the hit cartoon show, South Park.
The cause of death was not immediately known.
He was about to begin work on a new album for Stax, the soul record label he helped build to legendary status.
British soul star Jazzie B, who became friends with Hayes after they performed together in the 1990s, described him as "a really nice man" and "as cool as ice".
"He was an equal cornerstone to the evolution of hip-hop, what's come to be known as R&B, and urban music in general," he told BBC News.
"So there's absolutely no doubt that Isaac Hayes will be truly missed and he was a very influential part of music as we hear it today."
Collin Stanback from the Stax label told the Associated Press news agency that the star "embodies everything that's soul music".
He added: "When you think of soul music, you think of Isaac Hayes - the expression, the sound and the creativity that goes along with it."
In a statement released from The Recording Academy, the body behind the Grammys, president Neil Portnow called him a "true renaissance man".
He added: "After laying the groundwork for the Memphis soul sound through his work with Stax Records, his groundbreaking theme song and score for the movie Shaft cemented his status as a musical icon.
"The world has lost a true creative genius and a passionate humanitarian, but his indelible legacy will remain ever present."