Miranda Lambert, Nashville Star
In 2003, the "Platinum" singer auditioned for Nashville Star, which was basically country music's response to American Idol. Miranda appeared in the inaugural season of the show and ended up placing third, behind two guys who definitely don't have seven consecutive Academy of Country Music Female Vocalist of the Year awards to their names.
Fifth Harmony, The X Factor
Camila Cabello may have just announced her departure from the girl group, but looking back, she, along with Ally Brooke, Dinah Hansen, Lauren Jauregui and Normani Kordei were destined for stardom. Each auditioned as solo singers on The X Factor in 2012, but got cut just before the judges' house round.
Luckily, Simon Cowell and the other mentors decided the teens would fare much better as a group, and thus, Fifth Harmony was born. The girls finished in third place, but they've become the most successful act to come out of the U.S. version of The X Factor, with 10 million records sold and multiple awards to their name, they truly showed the world who's "Bo$$".
Tori Kelly, American Idol
Tori Kelly is no stranger to singing competitions. As a kid, she competed on TV contests Star Search and America's Most Talented Kids, the latter of which she actually won. However, her recording deal ultimately fell through, and in 2010 she auditioned for American Idol. Tori failed to make the top 24, but despite the rejection, she still found fame thanks to her enormous talent.
In fact, she's putting her knowledge of these contests to good use in her first major film debut in animated movie Sing, in which she plays Meena, an timid elephant who takes part in a singing competition.
Kacey Musgraves, Nashville Star
Miranda Lambert wasn't the only singer to find fame after Nashville Star. Kacey Musgraves competed in the contest in 2007 when she was just 18 years old and finished in seventh place. But the "Biscuits" hitmaker has no qualms about not winning the competition, previously telling Yahoo! Music, "It was a great platform to get myself kind of accustomed to being in the industry and seeing what it was like being away from my tiny little hometown in Texas."
One Direction, The X Factor U.K.
It's easy to forget that the biggest boy band in recent years got its start on The X Factor U.K., given the heartthrobs' success all around the world. Much like Fifth Harmony, Niall Horan, Liam Payne, Harry Styles, Louis Tomlinson and Zayn Malik auditioned in 2010 as solo artists but got cut.
Simon Cowell placed them together to form 1D and since then, they've won multiple awards, sold more than 20 million albums worldwide, and embarked on a number of high-grossing world tours. Despite the fact Zayn bowed out last year and the remaining foursome have been on hiatus, we're still keeping the faith we'll see a reunion soon.
Nicole Scherzinger, Popstars
Just before American Idol became a phenomenon, there was a TV series called Popstars on The WB, and it featured aspiring female singers aiming for a spot in girl group Eden's Crush. Among the five ladies who made the cut was Nicole Scherzinger, who was a clear frontrunner from the start. Eden's Crush had some success with their first and only top 10 album, but the group eventually disbanded.
Nicole found another squad with the Pussycat Dolls in 2003. And to come full circle, Nicole has even served as a judge on both The X Factor and The Sing-Off, helping to find new talent just like she was first discovered years ago.
Pentatonix, The Sing-Off
The acappella group actually first started out as a trio with high school friends Kristie Maldonado, Mitch Grassi and Scott Hoying. But in 2011, Scott found out about auditions for The Sing-Off, and recruited the final two members, Avi Kaplan and Kevin Olusola, to complete the fivesome. They met for the first time the day before the audition, and their chemistry was so undeniable that their talents took them all the way to win the title.
Jennifer Hudson, American Idol
Vocal powerhouse Jennifer Hudson was one of the favorites during season three of American Idol, but in one of the most shocking moments in the series history, she was cut from the contest and ended up in seventh place. But her pure talent helped her go far with not only her own singing career but movie career as well - she's the only Idol alum to have an Oscar to their name thanks to her moving role in Dreamgirls.
Now she's back on the big screen, lending her voice to animated movie Sing, alongside another Idol non-winner, Tori Kelly.
Lucy Hale, American Juniors
Long before Lucy Hale was getting threatening text messages from A, the Pretty Little Liars star first came into Hollywood with hopes of becoming a pop star. In 2003, she competed in the first and only season of American Juniors, the spin-off of American Idol. Instead of searching for one pop star, American Juniors sought the best five kids to form a singing group, and Lucy was the second to last contestant to make the cut.
Lackluster album sales led to the band's split in 2005, and Lucy went on to become the most successful American Junior with her acting career. But Lucy hasn't lost her passion for music and even released a country album, "Road Between", in 2014.
Carly Rae Jepsen, Canadian Idol
Before Justin Bieber helped catapult the "Call Me Maybe" singer into stardom, Carly Rae Jepsen was already a familiar face in her native Canada. In 2007, she auditioned for the fifth season of Canadian Idol and ended up coming in third place. She found success post-Idol in Canada, but it wasn't until Bieber's viral video with ex Selena Gomez and Ashley Tisdale that made Carly Rae an international superstar. And we've been so grateful to him for bringing her into our lives ever since.