Thanks to a Facebook campaign that capitalized on growing unhappiness with Cowell's cookie-cutter approach to pop stardom, the antiestablishment Rage Against the Machine came out ahead of Joe McElderry, winner of Cowell's popular "X Factor" TV competition.
The upset for the heavily favored McElderry represents a setback for Cowell, who has made millions on both sides of the Atlantic for his roles in "American Idol," ''X Factor," ''Britain's Got Talent" and other productions.
Rage Against the Machine finished first with a surge of support for their 1992 hit "Killing in the Name," which became the first Christmas No. 1 in Britain supported only by downloads.
The Facebook campaign was organized by an English couple Jon and Tracy Morter in a concerted effort to break Cowell's recent stranglehold on the holiday No. 1 song, a traditional source of status and bragging rights inside Britain.
"Rage Against the Machine was built for moments like this," the band's guitarist Tom Morello told The Associated Press. "We are honored to have the song that liberated the U.K. pop chart."
"Killing In The Name" surged in the last days of the competition to sell more than 500,000 copies in the past week, compared with sales of 450,000 for McElderry's single. It also set a record for most downloads in a single week. Morello said the band would donate the profits to the British homeless charity Shelter.
McElderry, a talented, baby-faced singer who is just 18, was gracious in defeat. He emphasized his satisfaction at winning last week's X Factor finals, which shot him from obscurity to national prominence.
"Fair play to the guys who have organized the Facebook campaign — it's been exciting to be part of a much-hyped battle and they definitely deserve congratulations," he said.
McElderry said he was "delighted" to have his debut single — The Climb — in the charts. The CD is prominently displayed in hundreds of British shops.
"It's been such an incredible couple of months, and I got the best Christmas gift I could ever have asked for in winning The X Factor," he said.
The Facebook campaign on behalf of Rage Against the Machine attracted nearly 1 million followers on Facebook, many of whom were exasperated with the way the winner of the X-Factor has dominated music charts in the run up to Christmas.
Morello said the campaign had delivered "a crushing defeat for bland pop music."
"There are other ways to make music than to stand in front of a panel and perform like a circus bear," Morello added. "Free expression, uncompromising content are sitting on top of the U.K. pop chart this week."
The list of past Christmas No. 1 winners includes the Spice Girls, the Beatles, Michael Jackson, Elvis Presley and perennial British favorite Cliff Richard, who triumphed with The Shadows in 1960 and again as a solo act in 1988.