Michael Jackson, 50, the dazzlingly talented Motown child star and pop innovator who defined the MTV era with his massively successful 1982 album Thriller, and remained a worldwide icon even as his achievements as an entertainer were overshadowed by child-molestation charges and personal eccentricities, died yesterday in Los Angeles.

Mr. Jackson, the songwriter and scintillating performer who proclaimed himself the "King of Pop," and whose appearance and skin color altered dramatically over the course of more than 40 years in show business, was rushed to the hospital from his home in Los Angeles yesterday.

He was not breathing when paramedics arrived, and was in a deep coma when the ambulance got to Ronald Reagan UCLA Medical Center, where he was later pronounced dead. The circumstances of his death were unclear.

The one-gloved singer unified the pop-music universe with hits such as "Don't Stop 'Til You Get Enough," "Beat It," and "Wanna Be Startin' Somethin,' " which represented a perfect synthesis of syncopated African American dance music and pure pop.

He was an elegant, acrobatic dancer who combined the grace of Fred Astaire with the physicality of James Brown. In remaking the pop-music world in the '80s, in his androgynous, Jheri-curled image, his music and celebrity achieved a global notoriety equaled in the second half of the 20th century only by Elvis Presley and the Beatles.

Mr. Jackson broke down racial barriers at MTV with his hit "Billie Jean," and was propelled to unprecedented levels of pop stardom when he did his trademark backward "moonwalk" on the 1983 television special Motown 25: Yesterday, Today, Forever. In the process, he changed how music was marketed: After Mr. Jackson and Thriller, which by some accounts is ranked the biggest-selling album of all time, it mattered just as much how you looked and moved as how your music sounded.

Mr. Jackson was about to attempt an epic comeback. He was scheduled to begin a record-breaking, sold-out 50-show engagement at London's O2 Arena on July 13. (In 2007, Mr. Jackson's '80s rival, Prince, played 21 sold-out shows at the arena.)

The shows, delayed from an original start date of July 8, were scheduled to take place over several months, stretching into 2010. Mr. Jackson was said to be training with body builder and Incredible Hulk star Lou Ferrigno, and questions about his health led London oddsmakers to take bets on whether the shows - the singer's first large-scale live performances in more than a decade - would go on.

Reaction to Mr. Jackson's death among musicians, celebrities, and fans was widespread around the world, with many fans expressing their grief on the Internet via the social media network Facebook and the microblogging service Twitter.

"I am absolutely devastated at this tragic and unexpected news," Quincy Jones, who produced Jackson's multimillion-selling trio of albums Off the Wall, Thriller, and Bad, said in a statement.

"To this day the music we created together . . . is played in every corner of the world and the reason for that is because he had it all. . . . talent, grace, professionalism and dedication. He was the consummate entertainer and his contributions and legacy will be felt upon the world forever. I've lost my little brother today, and part of my soul has gone with him."

Philadelphia International Records founders Kenny Gamble and Leon Huff, who worked with Mr. Jackson on The Jacksons (1976) and Goin' Places (1977) with his brothers Jermaine, Jackie, Tito, and Marlon, said in a statement: "Michael Jackson was a great and wonderful artist. He and his brothers came to work with us in 1976 as they were transitioning from Motown as the Jackson 5 to PIR as The Jacksons. With Gamble and Huff they were able to write and produce their own music. We are saddened by his death. His music and legacy will last a long time."

Shortly after the announcement of Mr. Jackson's death, bold-faced names from John Mayer to Lindsay Lohan began tweeting about the news. Ahmir "?uestlove" Thompson, drummer for the Philadelphia hip-hop band the Roots, wrote on Twitter: "I am devastated over this but we all have memories . . . i know he was mired in controversy the last decade of his life but I think it's time we let him rest in peace and learn to separate the ART from the ARTIST - that is the MJ I will forever remember."

Michael Joseph Jackson was born on Aug. 29, 1958, in Gary, Ind., the seventh of nine children in what, largely due to his own outsized talent, would become one of America's most illustrious musical families. Along with his brothers, including Randy, and sisters Rebbie, LaToya, and Janet, he was raised a Jehovah's Witness by his mother, Katherine, and followed in the musical footsteps of his father, Joe, a steel-mill worker and R&B vocalist.

Mr. Jackson would later recount how his childhood was filled with abuse, and that his early rehearsals with his brothers, with whom he began performing in 1964, were ruled by his father with an iron fist - or a leather belt.

He and his older brother Jermaine took on lead vocals by 1966. After recording for the Gary label Steeltown, they signed to Berry Gordy's already-storied, Detroit-based Motown in 1968 as the Jackson 5. Immediately, it was clear that the prepubescent Michael, with a bouffant Afro (and still with the natural color of his skin), was the star of the group, an uncommonly talented prodigy with a high-pitched voice able to powerfully put over a song with a passion and professionalism seemingly beyond his years.

Beginning in 1969, the first four Jackson 5 singles - "I Want You Back," "ABC," "The Love You Save" and "I'll Be There" - all topped the Billboard charts. In the early '70s, he also scored solo hits, including "Got To Be There," and "Ben," a tender love song to a celluloid rat that marked the beginning of a creepiness factor that would stick to Mr. Jackson over the years, as he made friends with Bubbles the Chimp and tried in the '80s to buy the bones of the Elephant Man.

Seeking to express themselves outside of the tightly controlled Motown music machine, the Jackson brothers signed with CBS Records in 1975 and began to record with Gamble and Huff for PIR.

In 1978, Mr. Jackson starred as the Scarecrow alongside his boyhood idol Diana Ross in the Hollywood musical version of The Wiz, and first collaborated with Jones, who would help take his music to its greatest heights. ("Divinity brought our souls together," Jones said yesterday.)

Jones, who had previously worked with Ray Charles and Frank Sinatra, helped Mr. Jackson find his adult voice. Their first album together was the kinetic Off the Wall, which had the No. 1 hits "Rock With You" and "Don't Stop 'Til You Get Enough," and went on to sell more than 7 million copies in the United States.

That was peanuts, however, compared with Thriller, which spawned seven Top 10 hits, and broadened Jackson's audience with contributions from Paul McCartney on "This Girl Is Mine," and guitarist Eddie Van Halen on "Beat It."

Mr. Jackson toured with his brothers on the 1984 Victory Tour, which stopped for four shows at John F. Kennedy Stadium in South Philadelphia in September, Mr. Jackson's last local performances. Standing atop a mid-1980s pop pyramid above Prince and Bruce Springsteen, with the richly rhythmic, vivedly exciting Thriller, Mr. Jackson created the blueprint for the pop mega-album.

His LP was filled with songs like the paternity suit fantasy "Billie Jean" which was brought to life in choreographed, brilliantly danced narrative-driven videos - the John Landis-directed horror homage "Thriller" clip stretched to 13 minutes - that set the pop standard for years to come.

The album won eight Grammys and, with U.S. sales of 25 million and millions more overseas, is considered one of the best-selling albums - perhaps the best-selling - with total sales estimated anywhere from 47 million to 100 million.

At the peak of his celebrity, Mr. Jackson's public life grew increasingly bizarre. His hair caught on fire during the filming of a 1984 Pepsi commercial. He purchased the soon-to-be-infamous Neverland Ranch in Santa Barbara.

And the oddly asexual pop star had a string of cosmetic surgery operations that continued to change his appearance. His skin kept mysteriously whitening, an alteration the singer would later blame on a rare condition called vitiligo.

Mr. Jackson again collaborated with Jones on the 1985 charity single, "We Are the World." The pair followed up Thriller in 1987 with the aggressively edgy and aggressively schmaltzy Bad, a slight comedown artistically and commercially but whose hits - "Smooth Criminal," "The Way You Make Me Feel," and "Man In the Mirror" - more than stand the test of time. It was a blockbuster, but did not equal Thriller, selling a paltry 8 million copies.

In retrospect, Bad was Mr. Jackson's last truly successful album. When he returned in 1991, at the dawn of the grunge era in popular culture, he began calling himself "the King of Pop." He split with Jones to work principally with New Jack Swing producer Teddy Riley. Though the album scored its share of hits - "Remember the Time," and the title track with its crotch-grabbing video - Mr. Jackson's music was soon completely overtaken by his off-putting image.

Often surrounded in public by children, he was accused in 1993 of molesting a 13-year-old boy, a case which was settled out of court. In 1994, Mr. Jackson attempted to create of royal pop union when he married Lisa Marie Presley, and offered Elvis's daughter a cringe-inducing kiss at that year's MTV Video Awards. The marriage lasted less than two years.

His 1996 album HIStory: Past, Present and Future packaged old hits with mostly forgettable new material, with the exception of a duet with his sister Janet. Later that year, Mr. Jackson married Debbie Rowe, and the couple had two children, son Prince Michael Jackson I and daughter Paris Michael Katherine Jackson. The couple divorced in 1999.

Mr. Jackson returned with a new album, Invincible, in 2001, working extensively with South Jersey producer Rodney Jerkins, and scoring modest hits with "You Rock My World" and "Butterflies."

By that point, however, the man who had, along with Madonna, done more than anyone to reshape pop music as a visual art form was so overshadowed by his image that escapades - like his 2002 dangling of his son Prince Michael II over a hotel balcony in Berlin - that his music could no longer be heard on his own terms.

He was perhaps the most exciting performer of his generation, known for his feverish, crotch-grabbing dance moves and his high-pitched voice punctuated with squeals and titters. His single sequined glove, tight, military-style jacket, and aviator sunglasses were trademarks second only to his ever-changing, surgically altered appearance.

"It seemed to me that his internal essence was at war with the norms of the world. It's as if he was trying to defy gravity," Michael Levine, a Hollywood publicist who represented Mr. Jackson in the early 1990s, said. He called Mr. Jackson a "disciple of P.T. Barnum" and said the star appeared fragile at the time but was "much more cunning and shrewd about the industry than anyone knew."

In 2005, he was cleared of charges he molested a 13-year-old cancer survivor at Neverland in 2003. He had been accused of plying the boy with alcohol and groping him, and of engaging in strange and inappropriate behavior with other children.

The case followed years of rumors about Mr. Jackson and young boys. In a TV documentary, he had acknowledged sharing his bed with children, a practice he described as sweet and not at all sexual.

Despite the acquittal, the lurid allegations that came out in court took a fearsome toll on his career and image, and he fell into serious financial trouble.

Singer Dionne Warwick said: "Michael was a friend and undoubtedly one of the world's greatest entertainers that I fortunately had the pleasure of working with. . . . We have lost an icon in our industry."

Hundreds of people gathered outside the hospital as word of his death spread. The emergency entrance at the UCLA Medical Center, which is near Mr. Jackson's rented home, was roped off with police tape.

"Ladies and gentlemen, Michael Jackson has just died," a woman boarding a Manhattan bus called out, shortly after the news was announced. Immediately, many riders reached for their cell phones.

So many people wanted to verify the early reports of Mr. Jackson's death that the computers running Google's news section interpreted the fusillade of "Michael Jackson" requests as an automated attack for about half an hour last evening.

In New York's Times Square, a low groan went up in the crowd when a screen flashed that Mr. Jackson had died, and people began relaying the news to friends by cell phone.

"No joke. King of Pop is no more. Wow," Michael Harris, 36, of New York, read from a text message a friend sent to his telephone. "It's like when Kennedy was assassinated. I will always remember being in Times Square when Michael Jackson died."

For more images and coverage of Michael Jackson's life, visit http://www.philly.com/michaeljacksonEndText

This article contains information from the Associated Press.

Contact music critic Dan DeLuca at 215-854-5628 or ddeluca@phillynews.com.