As American Idol 2 ends, what is in the stars for the winner? BBC News Online tracks the careers of the most popular contestants from the first series of American Idol and the UK's Pop Idol.
After winning the first series of American Idol, Clarkson mirrored the success of UK Pop Idol Will Young (see below) , notching up the best-selling US release for three years.
Kelly Clarkson narrowly beat Justin Guarini
Her first single, A Moment Like This, was rush released like Young's, selling 236,000 copies in its first week.
But then Clarkson disappeared to make a movie with American Idol runner-up Justin Guarini.
Her album, Thankful, also went to number one when it was released in April this year.
Her singing style has seen her compared to Mariah Carey, Whitney Houston and Celine Dion, and she also co-wrote part of her album.
The afro-haired former door-to-door salesman was a crowd favourite and narrowly lost out in the American Idol final.
Like Clarkson, he went straight to make the pair's movie, From Justin to Kelly, which sees the pair meet on a spring break and fall in love. It is released in the US on 13 June.
He has not yet released any material eight months after the first series of American Idol ended.
That will change when his debut album, TBD, comes out to coincide with the movie.
The normally fearsome American Idol judge Simon Cowell called Gray, who came fourth, "a world-class singer with superstar potential".
So she was signed to Cowell's RCA record label alongside Clarkson and Guarini.
Her debut album is on the horizon, but she has already launched an acting career, starring in four episodes of Fox school drama Boston Public.
She also has a writing credit and duets on Clarkson's debut album and is a member of a hip-hop dance company.
Will Young pipped Gareth Gates to win the gripping finale of the UK's Pop Idol after a record 8.7 million votes were cast.
Will Young: His first single was a record-breaker
His first release, Evergreen - originally recorded by boy band Westlife - became the fastest-selling UK single in history, shifting more than 1.1 million copies in a week.
He revealed he was gay one month after winning - but it did not appear to harm his career, scoring more chart-toppers with The Doors' Light My Fire and a duet with Gareth Gates.
Viewers have also voted him Television Personality Of The Year and he picked up a prestigious Brit Award for best breakthrough artist.
He may not have won, but his boyish looks and cheeky image meant he fitted the pop star stereotype more than Young.
Gareth Gates recorded a charity version of Spirit in the Sky
He has had two solo number one hits, plus a Comic Relief charity chart-topper with comedy TV family The Kumars.
Like Young, he has also expanded his appeal outside the UK to countries including Germany, Holland and Norway.
But also like Young, his debut album, What My Heart Wants To Say, has dropped out of the UK top 100.
The Scottish singer proved it is possible to salvage a reality TV reputation after going from national laughing stock on Popstars to third place on Pop Idol.
Darius Danesh began a UK tour at the start of May
Not signed by Simon Fuller, he tried to escape the stigma of manufactured pop and co-wrote his debut number one single, Colourblind - which seemed radical compared with his rivals' cover versions.
But despite the modicum of credibility, his following singles failed to do so well. Incredible, his third release, entered the chart at number nine in March.
She came fourth on the UK show, and was best pals with Gareth - leading to constantly denied rumours of a romance.
Zoe Birkett toured with Will Young and Gareth Gates
She was also the warm-up act for Gates and Young when the trio went on a UK tour soon after the series finished.
But her solo career has failed to take off in the same way, with one single that reached number 12 in January.
The only UK contestant signed by Cowell apart from Young and Gates, Whatmore was given an image as a sultry, sexy pop babe.
Sarah Whatmore: Album due in the summer
Her first single, When I Lost You, reached number six in September, with the follow-up, Automatic, just missing the top 10 in February.
But she has also shown songwriting promise, co-writing fellow hopeful Zoe Birkett's debut single.
Whatmore is still signed and is currently in the studio, working on her debut album, Living Proof, which is due in the summer.
Having reduced judge Pete Waterman to tears with one performance on the show, her solo career failed to take off.
Rosie Ribbons was given a bad girl makeover
She was given a make-over as the bad girl of pop and released two singles, which got to 12 and 19.
But that was not good enough for her record label, Telstar, who dropped her earlier this year.
Waterman's label PWL says it knows nothing about rumours the impresario was set to rescue her career.
Evetts began by recording a charity single with four West Midlands police officers and comedian Joe Pasquale under the name Copstars in aid of a Birmingham hospital.
Hayley Evetts has dabbled in TV presenting
But things got better when she was chosen to present ITV2 coverage of Popstars: The Rivals, and there were reports that she would be asked back to help present Pop Idol II.
Her first solo single, "a dance version of a famous 80s ballad", is to be released this summer.
She stays in the gossip columns thanks to a relationship with Baywatch star Jeremy Jackson.
The Eurovision Song Contest is said to be cursed, and Jessica Garlick sunk without a trace since representing the UK in 2002.
Jessica Garlick has disappeared from the public view since Eurovision
Her song, Come Back, came third behind the Latvian entry and reached number 13 in the UK charts.
She followed it with low-key shows around the UK - but went to the US with Evetts to make a guest appearance on American Idol 2.
Producer and American Idol judge Randy Jackson was so impressed that he reportedly signed her with the intention of launching her on the US charts.