Dio had been suffering from stomach cancer
American heavy metal singer Ronnie James Dio, who replaced Ozzy Osbourne in Black Sabbath, has died at the age of 67, his wife and manager have said.
Dio had been suffering from stomach cancer.
Before joining Black Sabbath he sang in Rainbow - formed when Ritchie Blackmore left Deep Purple - and later in Heaven & Hell and the self-titled band Dio.
Dio's wife Wendy paid a loving tribute to her husband on his website, saying: "Today my heart is broken."
She said her husband had passed away on Sunday morning.
'Live on forever'
"Many, many friends and family were able to say their private goodbyes before he peacefully passed away," she wrote.
"Please know he loved you all and his music will live on forever."
Black Sabbath guitarist Tony Iommi also paid tribute: "I've been in total shock. I just can't believe he's gone.
"He loved his fans so much. He was a kind man and would put himself out to help others. I'll miss you so much my dear friend," he wrote on his website.
As a mark of respect, the Download Festival will re-name the second stage at this year's festival the Ronnie James Dio stage.
Dio was being treated at a hospital in Houston, Texas, according to his website.
The statement of his death was confirmed by Los Angeles publicist Maureen O'Connor, Associated Press reported.
Dio revealed last summer that he was suffering from stomach cancer shortly after wrapping up a US tour.
He was born Ronald James Padavona to an Italian-American family in Portsmouth, New Hampshire.
He is said to have got the idea for his name change from a mobster called Johnny Dio.
Rated one of rock's most powerful vocalists, he rose to fame in the mid-1970s as lead singer of Rainbow, before replacing Osbourne in Black Sabbath in 1980.
Later that year the band released their ninth studio album, Heaven And Hell, considered by many fans as one of the greatest heavy rock LPs of all time.
Dio's solo hits included Rainbow In The Dark, The Last In Line, and Holy Diver.
"He possessed one of the greatest voices in all of heavy metal, and had a heart to match it," Twisted Sister guitarist Jay Jay French, whose band used to tour with Dio, told AP.