Mitch Mitchell drumming with the Jimi Hendrix Experience on the Lulu Show, 1969.
Mitch Mitchell, the British drummer in the seminal 1960s band the Jimi Hendrix Experience, has been found dead in his US hotel room, authorities say.
The 61-year-old was discovered in the Benson Hotel in Portland, Oregon, in the early hours of Wednesday.
A medical examiner told the Associated Press news agency that his death appeared to be from natural causes, but said there would be an autopsy.
Hendrix died in 1970 and the band's bassist Noel Redding died in 2003.
Mitchell, from Ealing in west London, had been touring with the Experience Hendrix Tour.
'Rock 'n' roll hero'
Janie Hendrix, chief executive of the tour and step-sister of Jimi Hendrix, paid tribute to Mitchell.
The band was one of the most influential of the 1960s
"He was a wonderful man, a brilliant musician and a true friend," she said.
"His role in shaping the sound of the Jimi Hendrix Experience cannot be underestimated."
Terry Stewart, chief executive of the Rock and Roll Hall of Fame and Museum, also paid tribute to Mitchell.
He said the musician had added a "strictly percussive element to a lead instrument".
He added: "His interplay with Jimi Hendrix's guitar on songs like Fire is truly amazing.
"Mitch Mitchell had a massive influence on rock 'n' roll drumming and took it to new heights."
Mitchell performed on Hendrix classics such as Are You Experienced? Electric Ladyland and Axis: Bold As Love.
The top session drummer also played with the likes of Eric Clapton, John Lennon, Keith Richards and Muddy Waters.
Mitchell drummed for Hendrix at his legendary Woodstock performance
Bob Merlis, a spokesman for the tour, called his death "devastating".
He had seen Mitchell perform two weeks ago in Los Angeles and the drummer appeared healthy and upbeat, he said.
Blues-rock guitarist Kenny Wayne Shepherd, who is also part of the tour, said Mitchell was to drums what Hendrix was to guitar.
"Today many of us have lost a dear friend, and the world has lost a rock 'n' roll hero," he said.