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They have reduced the average contestant to tears, made them flirt outrageously or threaten to set their mums on them. It's fair to say that the X Factor wouldn't be the success it is today if it wasn't for its panel of judges.
With the series due to start again this month, we look at Simon, Cheryl, Louis and Dannii and their hopes for the show in 2009.
:: Simon Cowell
Credentials: Music tycoon turned TV entrepreneur, with a hand in the sales of over 150 million records worldwide, including more than 100 No 1 records in the UK and the US. Also involved with major TV shows on both sides of the Atlantic, including American Idol and Britain's Got Talent.
X Factor track record: Been winning judge on two occasions, with Steve Brookstein in 2004 and Leona Lewis in 2006.
Cowell comments on this year's auditions: "There have been some outstanding auditions this year and some totally bizarre ones... A lot can change as the series goes on and acts develop differently. We have had great performances from acts in each category so it's going to be a great competition and I think everyone will be surprised by some of the auditions who really stand out."
On what makes the X Factor: "I think most of the time you just know - when you have a really special artist walk on stage it's immediate. I'm very instinctive and you can feel it, even the audience reaction, the atmosphere just changes - someone brilliant just walks on stage and you know they've 'got it'."
Simon says: (When asked which category he'd like this year) "The category that's going to win."
:: Cheryl Cole
Credentials: Enjoyed major success with chart-topping group Girls Aloud, and had her own experience of TV talent shows as a contestant on Pop Stars: The Rivals.
X Factor track record: Winning judge in her debut year as mentor to Alexandra Burke in 2008.
Cole comments on this year's auditions: "The new look auditions benefit not only the acts but also us, as the audience let us know if they think differently to us about an act and sometimes we change our mind.
"It's great for us as judges because we get to see how an act can handle performing on stage to a crowd earlier in the competition process and they get this fantastic opportunity to perform on stage."
On what makes the X Factor: "It's something you can't describe. Alex had it for me - that sparkle, the performance, the vocal, the personality, she had it all."
Cheryl says: (On whether she's getting her Girls Aloud bandmates involved this year) "I don't have any choice in the matter, the girls absolutely love the show and all have their own opinions on everything and always let me know what they're thinking!"
:: Louis Walsh
Credentials: The king of Irish pop has had major chart success with acts including Boyzone and Westlife.
X Factor track record: A winner with Shayne Ward in 2005.
Walsh comments on this year's auditions: "I think the element that I enjoyed most about the new look auditions were the audience. Every city we've visited felt different every time and there's nowhere to hide!"
On what makes the X Factor: "It's really hard to define or find - I think it's someone with talent, likeability, good work ethic, personality and charm. It's somebody that's got everything!"
Louis says: (On last year's runners-up, who he mentored) "I'm so pleased and proud of JLS. They worked so hard on the show last year and have worked extra hard since it finished, as a group they deserve every success."
:: Dannii Minogue
Credentials: Former child star Dannii has gone from acting in Home And Away in her native Australia to being an international chart-topping solo artist. Not to mention being sister to pop princess Kylie.
X Factor track record: Was winning judge in 2007 when Leon Jackson won, and had runner-up Rhydian Roberts in that year as well.
Minogue comments on this year's auditions: "We've had an amazing Afro rocker and he totally took over the stage! His first performance was pure perfection, and his second bordered on scenes from the movie classic This Is Spinal Tap - TV gold!"
On what makes the X Factor: "It's something you can't describe or bottle, but you know when you see or hear it."
Dannii says: (On whether she will have celebrity pals helping her choose her finalists) "Of course. That is crunch time for deciding the final three for Team Minogue, so it's very important to get it right and have someone to bounce off - I just can't tell you who yet!"