Las Vegas ? John Entwistle, the quiet, efficient bass player who co-founded The Who and helped it become one of the most dynamic and successful rock bands in history, was found dead of an apparent heart attack Thursday in his Las Vegas hotel room. He was 57.

Entwistle was on medication for a heart condition, according to band member Steve Luongo.

The Who bassist John Entwistle performs at a Aug. 25, 2000, concert in Albuquerque, N.M. Entwistle, 57, was found dead Thursday in his Las Vegas hotel room, according to MCA Records and Clark County Coroner's Office.

An autopsy was scheduled for today, but Clark County officials said there was nothing suspicious about the death, which came nearly a quarter-century after the band’s original drummer, Keith Moon, died of an overdose at age 31.

The Who was to play today at the Hard Rock Hotel-Casino, the first date of a three-month, nationwide tour. That show and another scheduled for July 1 in Los Angeles were canceled. The rest of the tour was undecided, said Beckye Levin of Clear Channel Entertainment.

The group, founded in London in the early 1960s, was part of the British rock invasion along with the Rolling Stones, the Beatles and others. They were the voice of a new breed, with a parade of guitar-driven hits that included “My Generation,” “I Can See For Miles,” “I Can’t Explain,” “Substitute,” “Pinball Wizard,” “Won’t Get Fooled Again” and “Who Are You.”

Their concerts were literally explosive a fusion of audacious acrobatics, martial precision and high octane rock ‘n’ roll that blew away audiences and left the stage and their instruments a smoldering wreck. The group was one of the premier rock bands in the world throughout the 1970s and sold millions of albums.

“A lot of our fans liked us because we made mistakes. It made us look more human. And then the fact that we could actually sort of burst out laughing on stage when we made a real bad blunder,” Entwistle told The Associated Press in a 1995 radio interview.

Entwistle allowed his fingers to literally race over his instrument, but he stood silently on stage a stark contrast to the antics of guitarist Pete Townshend and lead singer Roger Daltrey.

Ray Manzarek, keyboardist for the Doors, called Entwistle “one of the great, great rock ‘n’ roll bassists of all time. A real genius.”

“He just was the most humble rock star I have ever met, besides having the best hands of any bass player in the history of rock and roll,” added rocker Sammy Hagar.

Entwistle’s song writing contributions to the band were minimal compared with the prolific Townshend. The bass player penned “Boris the Spider” and “My Wife,” among others none of them big hits. Yet he was the only member of the band with formal musical training.

He was among the first in rock to experiment with the six- and eight-string bass and he also played the French horn.

“As a musician, he did for the bass guitar what Jimi Hendrix did for the guitar,” said Luongo, 49, who played drums in The John Entwistle Band for the last 15 years.

Entwistle was born Oct. 9, 1944, in London. He met Townshend and Daltrey in his high school years and by 1964 the band was born.

The Who was inducted into the Rock and Roll Hall of Fame in 1990.