Entwistle, known for stoically holding the bottom line on stage while his hyperkinetic bandmates wreaked havoc around him, was found about noon in his hotel room at the Hard Rock Hotel and Casino, the victim of an apparent heart attack, according to local authorities. He was 57.
Steve Luongo, the drummer and comanager of the John Entwistle Band, said the bassist had been taking medication for a heart condition.
An avid painter and caricaturist, Entwistle had arrived in Las Vegas before his bandmates for an exhibition of his artwork. The Who, which has disbanded and regrouped countless times in the past 20 years, was slated to begin a three-month tour at the Hard Rock on Friday. The group has canceled dates at least through the weekend, and the fate of the tour is in doubt.
The band's manager, Robert Rosenberg, said he was "saddened and shocked" by the news. Surviving band members Pete Townshend and Roger Daltrey had no immediate comment.
The Hard Rock has become a makeshift shrine, as hundreds of fans congregated at the casino's restaurant, many bringing flowers and Who-related trinkets. The marquee outside the resort read: "John Entwistle...rest in peace. You will be missed by all."
Entwistle was born October 9, 1944, in Chiswick, England. A musical prodigy, Entwistle and high school buddy Townshend formed a Dixieland combo together in London, with Entwistle playing trumpet and Townshend on banjo. They eventually hooked up with Daltrey in an edgy rock outfit called the Detours. By 1964, with spastic drummer Keith Moon on board, the band had morphed into the Who.
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> With Townshend the driving creative force, Daltrey's primal rock scream and the instrumental wizardry of Entwistle and Moon, the Who ranked behind only the Beatles and the Rolling Stones in the British invasion.
They charted with tracks like "I Can't Explain," "Substitute," "I Can See for Miles," "Magic Bus," "My Generation" and Entwistle's signature novelty tune, "Boris the Spider," and turned the genre on its head with the groundbreaking rock operas Tommy and Quadrophenia. Who's Next is considered one of the greatest albums in rock history, featuring FM staples "Behind Blue Eyes," "Won't Get Fooled Again," "Baba O'Riley," "Bargain" and Entwistle's "My Wife."
As good as the studio albums were, the rockers earned the reputation of being the finest (and, according to the Guinness Book of World Records, loudest) live band of the '70s, and they produced what is arguably rock's greatest concert album, 1970's Live at Leeds.
Their stage antics were infamous: Townsend's frantic windmills and stage jumps, Moon's wild man act behind the drum kits, Daltrey's microphone spinning and sprints across stage all anchored by the impassive Entwistle. At the end of a set, no instrument was safe.
During a concert at Britain's Rikki Tik Club in May 1966, Townshend whacked Entwistle in the head with his guitar; the following year, as the band ended a performance on The Smothers Brothers Comedy Hour, Moon detonated an explosive that destroyed his drum set, shocked the audience and thrashed Townshend's eardrums.
Following their 1975 tour, the band took a three-year break, during which time Entwistle worked on his side projects, Ox (after his nickname) and Rigor Mortis.
The band regrouped in 1978 to record Who Are You (the title cut now serves as the theme to CSI). But shortly after the album's launch, Moon was found dead in his London flat after overdosing on anti-alcoholism pills.
Aside from forming to play a Live Aid set in 1985, the oft-squabbling surviving members performed two farewell tours, in 1982 and 1989, and took Quadrophenia around the world in 1996 and 1997.
After the '97 trek, Entwistle toured with the John Entwistle Band and released the concert album Left for Live in 1999.
The Who got together again for more shows in 1999-2000, amid talk of returning to the studio to record a new album.
That never came pass, however. The band did turn in a blistering set for last fall's Concert for New York and, two weeks ago, released a new double-disc greatest-hits album, The Ultimate Collection.
The Who was inducted into the Rock Hall of Fame in 1990 and received a Lifetime Achivement Grammy in 2001.
As a testatment to his musical genius, Entwistle outranked Paul McCartney, Led Zeppelin's John Paul Jones and Cream's Jack Bruce as Total Guitar magazine's "Bassist of the Millennium."
"The Ox distills inspiration, technique and that fine edge of madness that separates the great from the merely good," the magazine declared.
Adds Luongo, who played with Entwistle for 15 years: "As a musician, he did for the bass guitar what Jimi Hendrix did for the guitar."
Entwistle was married twice and had a son, Christopher, from his first marriage.