As "American Idol" celebrates its 500th episode & Season 13 comes to a close, here's our countdown of "American Idol" alums' biggest Hot 100 hits ever - and the untold stories behind the songs.

60

"Gallery" - Mario Vazquez

Hot 100 Peak: No. 35 (2006)

One month after Ne-Yo topped the Hot 100 with his debut chart single, "So Sick," J Records released this single, written by Ne-Yo (under his real name, Shaffer Smith) and Tor Erik Hermansen  and Mikkel Eriksen, the Norwegian production team known as Stargate. When Vazquez was named a top 12 finalist for season four of Idol, some people thought the Bronx-born singer would go far in the competition. But Vazquez had two surprises in store: first, he dropped out of "Idol," citing "family" reasons, and second, despite leaving the show, he was signed to a label deal by Clive Davis. "Gallery" was his only song to appear on the Hot 100.

59

"Best Days of Your Life" - Kellie Pickler

Hot 100 Peak: No. 46 (2009)

Taylor Swift doesn’t only write songs about her own break-ups. She was on tour with Pickler and Brad Paisley when the two women wrote "Best Days of Your Life," based on Pickler’s broken relationship with a boyfriend. Swift sang backing vocals on the track. Pickler has released nine singles to date and this is the only one to make the top 10 of the Hot Country Songs chart. It’s her highest-ranked title on the Hot 100.

58

"Wasted" - Carrie Underwood

Hot 100 Peak: No. 37 (2007)

Songwriter Troy Verges had written "Wasted" in his title book and batted it around with Hillary Lindsey and Marv Green. "It took about three hours to write," Verges recalls. "We played with some different stories and characters. When we were going to demo it, there was an additional second verse and we felt like that was too much. It took too long to get to the second chorus, so we yanked it out. That song was a real education for me in fine-tuning a song during the demo process. It’s a big melody. Not everyone can sing those kinds of songs. Hillary is a great singer in her own right, but Carrie just owned that song in such a way that it made it hers. It’s one of the best vocal performances beating the demo I’ve ever heard."

57

"If I Had You" - Adam Lambert

Hot 100 Peak: No. 30 (2010)

Lambert says that Swedish writer/producer Max Martin and his team had already started writing this song when they were asked to send more music for the season eight runner-up's first album for 19/RCA. Lambert believes that Martin then wrote some lyrics especially for him, including, "Got the eye liner and the right amount of leather."

56

"Life After You" - Daughtry

Hot 100 Peak: No. 36 (2010)

Daughtry was touring with Bon Jovi when Chris got a call from Chad Kroeger of Nickelback. "He wanted to send me a song he was writing," says Chris. "He said if I didn't like it, he was sending it to Keith Urban. I lived with the song for a year and wasn't sure if it was for us. But we couldn't get it out of our heads. I wrote the bridge and Chad signed off on it." "Life After You" was the second single from the "Leave This Town" album following "No Surprise."

55

"When I See U" – Fantasia

Hot 100 Peak: No. 32 (2007)

The song was composed for Geffen artist Tori Kelly, who recorded it on her 12th birthday, according to co-writer Sam Watters. He says the young singer was "shockingly good." Then there was a regime change at the label and Kelly was dropped (she later auditioned for season nine of "Idol"). Bruce Waynne of the Midi Mafia production team played the song for Fantasia, who recorded it for her second album, but not before doing some research. "I started back at 'Idol' and went through all of those songs and what did people say and what did they like," the season three winner explains. "Then I went through my first album, 'Free Yourself,' and I got it. People like to hear me sing from my soul, from my heart. They don't want me to hold anything back. I have to stay true to myself and that's what this album was."

54

"All-American Girl" - Carrie Underwood

Hot 100 Peak: No. 27 (2008)

Based on their success with "Don't Forget to Remember Me," Kelley Lovelace and Ashley Gorley were scheduled for a one-day writing session with Underwood. They completed one song and figured that was it. "Carrie said, 'That didn't take long. I guess we've got time to write another one,'" says Lovelace. He pitched a song fragment he had for a song called "All-American Girl." "Carrie said, 'It's not about me, is it?' I said, 'No, it's about this guy who wanted a boy but has a daughter.' She said it was like her dad when he had her. From there, it took two-and-a-half hours. I hate to say it was magical, but the chemistry was perfect. Ashley and I were really excited. We went out in the parking lot, looked at each other and said, 'What the hell just happened?'"

53

"Last Name" - Carrie Underwood

Hot 100 Peak: No. 19 (2008)

"It was written the first day I wrote with Carrie and Hillary Lindsey," says Luke Laird. "Carrie had been in Las Vegas for the ACMs and we were just making up a story about Vegas. Carrie and Hillary started rapping on the verses." Lindsey confirms, "We had a blast writing that song. There were three girls in the room and Luke. Carrie told us about her trip to Vegas where she met a cute guy on the dance floor. The rest wasn't true. It was fun."

52

"Light On" - David Cook

Hot 100 Peak: No. 17 (2008)

When Cook's management played some songs for him to consider for his first post-"Idol" album, they prefaced "Light On" by telling him that it was written by Brian Howes and a gentleman named Chris Cornell. Yes, that Chris Cornell, from Soundgarden and Audioslave. "Any Chris Cornell song would be a challenge vocally," says Cook. "He's an amazing singer. I was really excited about that song; it was one of the first ones I cut." It was also the first single released from Cook's self-titled debut for 19/RCA. Cook and Cornell finally met – but much later, at the ear, nose and throat doctor. "I was sick and he was there with a family member," Cook explains. "The doctor put Chris in my room and said, 'You guys should meet.'"

51

"Just a Dream" - Carrie Underwood

Hot 100 Peak: No. 29 (2008)

"Gordie Sampson, Steven McEwan and I would camp out and just write," says Hillary Lindsey. "I think the music was [composed previously]. We had the music and the melody and the verses started flying out. It was clear it was about a girl going to a wedding but she was really going to a funeral. I called my mom about what you put in a shoe. If I'm writing a redneck song about rednecks fishing, I'll call my dad. We had the chorus with the hook, 'It was just a dream.' We were worried it was too clichéd, but then decided who cares if it's a cliché, when it's the truth."

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