The one you love to hate: Before X Factor, there was Idol — and Cowell was king. The biting Brit is largely responsible for the explosion of singing competitions in the U.S. and U.K., with a hand in multiple franchises on both sides of the pond. Cowell's signature snark made him the love-to-hate favorite among viewers until his departure from the program in 2010.
The one who won't leave: Until now, Randy "The Dawg" Jackson has been the lone surviving member of the original judges' panel — keeping his seat for a whopping 12 seasons. His fair and honest critiques made Jackson a consistent contributor to the program. With season 13 on the horizon, he'll continue with the show in a reduced capacity as a mentor to the contestants.
The one with all the quirks: Straight up, there is no one else quite like Paula Abdul. The singing/dancing phenom served as the panel's lone female from 2002-09, with her sometimes bizarre, light-hearted antics bringing balance to Cowell's mean-spirited critiques. The love-hate dynamic between Abdul and Cowell left viewers craving more — so much so, that the Brit invited Abdul to reunite with him on the first season of the U.S. X Factor. Alas, their short-lived reunion lasted only one season.
The mainstay: Ryan Seacrest has been with the program since its very first episode and shows no signs of slowing down. Even with an upcoming gig on NBC's Million Second Quiz and a longstanding job hosting ABC's New Year's Rockin' Eve, Seacrest has one year left on his current Idol contract. Producers have described Seacrest as the "glue" that holds the show together, while he has dubbed himself the program's "traffic cop."
The one that got away: Brian Dunkleman shared hosting duties with Seacrest on the show's first season. But where is he now? The actor-comedian can be seen doing stand-up from time to time at Los Angeles comedy clubs The Laugh Factory and The Improv.
The one you forgot about: Ellen DeGeneres is a media mogul in her own right, with 13 Emmy awards to her name and a nationally syndicated talk show. Next year, she'll return to host the Academy Awards. But her turn on Idol was not so memorable, as the LGBT icon served just one season as Abdul's replacement in 2010. For her part, DeGeneres has said that the series just "didn't feel like the right fit."
The songwriter: Kara DioGuardi found herself cast as the fourth judge on an already established panel that included Cowell, Jackson and Abdul — no small task. Though she stayed on for another season, with DeGeneres replacing Abdul, DioGuardi has undoubtedly had more success behind the camera, penning tunes for the likes of Kelly Clarkson, Allison Iraheta, David Archuleta, Carrie Underwood, Katharine McPhee and Adam Lambert, among others. She also wrote the season-eight single, "No Boundaries."
Exiting the program after two seasons, DioGuardi went on to be head judge on Bravo's Platinum Hit.
The favorite: Jenny From the Block made her American Idol debut in the show's 10th season as part of a career comeback. She returned for season 11, but did not sign on for 12 after an agreement on compensation reportedly could not be reached.
Absence must make the heart grow fonder, as producers were said to be eager to get J.Lo back into a judge's seat for the upcoming season 13.
The crazy one: The Aerosmith rocker signed on alongside Jennifer Lopez for the show's 10th and 11th seasons, and while his bizarre "Say what?" comments proved endearing at first, viewers eventually tired of Tyler's antics.
But there were no hard feelings about Tyler's exit, as the legendary singer showed up — in drag — for a fake audition of his own during the 12th season.
The diva: Mariah Carey's arrival on the Idol panel received much fanfare — that is, until an up-and-coming hip-hop superstar stole her thunder. Carey was the first new addition to season 12, joining Randy Jackson and Keith Urban on the panel. But her presence on the show quickly became more about catfights and egos and less about pedigree. Let's just say her exit at the end of the season was not unexpected.
The Queen B: Barbie, that is. Not one to take anything lying down, Minaj seemed to be constantly on the offensive during her time on season 12. While her ongoing feud with co-panelist Mariah Carey was rumored to have been a publicity stunt, the conflict didn't go over well with viewers. Minaj promptly exited the show at the end of the season.
The boring one: Keith Urban is a successful and sane artist with a career worth admiring, but when it comes to excitement — it's just not there. The country crooner is certainly easy on the eyes, and that accent is nothing to sneeze at, but reality TV might be the one place where his manners and courtesy fall in the "cons" column.
The newbie: No stranger to Idol, Harry Connick Jr. has appeared on the program many times as a mentor and a performer. Now, he'll make it official as a judge, filling the third vacant seat alongside Jennifer Lopez and Keith Urban. How will he hold up in the hot seat? Hit the comments and share your thoughts on his casting.