John Entwhistle, the bass guitarist for the rock band The Who was found dead in a Las Vegas hotel room last night.
A spokeswoman for the Clark County Coroner's Office confirmed that the body of the 57-year-old musician was discovered in the Hard Rock Hotel in the city and his next-of-kin have been informed.
It is believed he died of a heart attack.
Robert Rosenberg, the manager of The Who, said he was "saddened and shocked" by news of Entwistle's death, on what was the eve of the band's US tour.
Born in Chiswick in west London in October 1944, Entwistle studied piano and played French horn for a youth orchestra before joining The Who.
During his rock career, he was known for playing without emotion, in stark contrast to the wild antics of the other band members, lead singer Roger Daltrey, guitarist Pete Townshend and drummer Keith Moon, who died of a drug overdose in 1978 in his London apartment, aged 31.
The Who formed in London in 1964 and were considered to be stalwarts of the Sixties Mod scene. The band were later renowned for the rock operas Tommy and Quadrophenia and had hits in four decades.
The band retired in 1982 after a concert in Toronto, but they reunited and had toured frequently in recent years. The Who's US two-month tour was due to kick off tomorrow at the Hard Rock Hotel.