The Who’s John Entwistle died in Las Vegas Thursday (6/27) as the band was about to embark on a North American tour. The first date was scheduled for Vegas Friday night (6/28). News of the bassist’s death was confirmed by the Clark County Coroner’s office. He was 57.

Entwistle, known by fans and friends as "The Ox" or "The Quiet One," reportedly died in his sleep at the Hard Rock Hotel and Casino, said coroner Ron Flud. He was found in his hotel room by his assistant early Thursday morning. An investigation is underway to determine the exact cause of death.

The three-month summer tour, which was to kick off Friday at the Joint, was scheduled to hit Los Angeles Monday (7/1) at the Hollywood Bowl. With Entwistle's death, The Who are down to just two original members, singer Roger Daltrey and guitarist/songwriter Pete Townshend. Original drummer Keith Moon died of an accidental pill overdose in 1978.

In addition to his recordings with the Who, Entwistle released a half-dozen solo albums. He was also a graphic artist, drawing the cover art for The Who By Numbers. Entwistle took the lead on a handful of Who songs, most definitively on "Boris the Spider" and "My Wife."

Entwistle was born in the London suburb of Chiswick on Oct. 9, 1944. He joined Daltrey in a forerunner of The Who in the early 1960s while working as a tax clerk. The band ultimately took shape in 1964 and made an immediate impression.

He told a reporter in 1988: "When I do a gig, people shout out, ‘Don’t ever stop,’ and as long as people keep shouting that, I’ll carry on. It keeps me alive. It keeps me happy. I don’t feel that because I’m over 40 I should stand aside. I’m going to play until I decide that I’m not good enough to play any more. And I don’t think that’s going to happen."