Blair Waldorf from Gossip Girl became an iconic mean girl. No one could imagine that behind that cold-hearted, smart young girl there is a sweetheart like Leighton Meester. This great actress has had a very colorful career in her short 34 years of life. She started working really young and has quite a resume that will undoubtedly get larger in the years to come.

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She's done almost everything, from thrillers to musicals, and since in addition to being an actress she's an amazing singer, she has also worked on the soundtrack of some of her projects. Here are a few of her many incredible roles.

10 She Was In 'Law & Order'

Leighton Meester, Law and Order
via US Weekly

Not many people remember since back then Leighton Meester wasn't the movie star she is now, but in her beginnings, she appeared on an episode of the most famous police drama in the world, Law & Order. It was her acting debut, and she was only 13 when she got the part. She played Alyssa Turner, the best friend of the murder victim. She was just a kid, but even then her talent was plain to see. After that, it was only a matter of time before she became a force to be reckoned with in showbusiness.

9 Her Role In 'Veronica Mars'

Leighton Meester, Veronica Mars,
via Twitter

Although Blair Waldorf is the character that everyone knows Leighton for, Gossip Girl wasn't the first series she had to play the mean, popular girl. In 2004, she had a recurring role in the series starred Kristen BellVeronica Mars. The series was set in a fictional town in California named Neptune, and Leighton played the Neptune High mean girl Carrie Bishop. She did a great job with the part, but unfortunately, when it was time to film the Veronica Mars movie, she had to be recast because she was busy with another project.

8 She Guest-Starred In 'CSI: Miami'

Leighton Meester, CSI Miami
via PoGDesign

CSI: Miami is one of the best crime series around, it's been a commercial success and it's had glowing reviews. So when in 2007 Leighton was offered the opportunity of guest-starring in the show, she immediately said yes.

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She appeared in an episode of the fifth season of the series, titled Broken Home, that told the story of the investigation of the double murder of a babysitter's parents. She portrayed Heather Crowley, the babysitter who finds out about her parents' terrible fate while she's working.

7 She Had A Role In 'Entourage'

Leighton Meester, Entourage
via Pinterest

HBO's drama Entourage was a roaring success, and it aired for eight seasons from 2004 to 2011. And during the fifth season, Leighton was offered a recurrent role in the show. She played the role of Justine Chapin, a pop singer that dates Vincent "Vince" Chase, but since she wants to stay a virgin, they can't have sex. She did a duet with another guest star, Tony Bennett, which she then reprised on the Entourage movie that came out in 2015.

6 She Was The Star In 'Drive-Thru'

Leighton Meester, Drive Thru
via IMDb

In 2007, Leighton Meester starred in a horror movie titled Drive-Thru, where she played Mackenzie Carpenter. Mackenzie was throwing a party with her friends -one of them portrayed by Penn Badgley, who would later become her co-star when they decide to use a ouija board. Unsurprisingly, this unfolds catastrophic events that she and her friends have to resolve before it's too late. Leighton didn't only star in this film but she also helped with the soundtrack, providing her song Inside The Black.

5 She Starred In 'Country Strong'

Leighton Meester, Country Strong
via IMDb

The country musical drama Country Strong came out in 2010, and Leighton starred alongside the incredible Gwyneth Paltrow. She did an amazing job, and everybody seemed to agree. In fact, The Boston Globe raved about her performance.

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"But Meester is the best thing in the movie. She’s just doing Reese Witherspoon’s June Carter Cash in 'Walk the Line' with dabs of Miley Cyrus and Kellie Pickler. But it’s not an impersonation; it’s a performance with its own comedy and sweetness."

4 Her Work In 'The Roommate'

Leighton Meester, The Roommate
via Pinterest

Leighton got the lead in yet another horror movie in 2011, proving once again that she's great at playing those types of roles. She portrayed Rebecca, a woman who becomes obsessed with her roommate Sarah. When asked about what drew her to the movie, she said it was her character.

"I love to break down and see where I can relate to somebody and find the humanity in them, and I want to care about my character and love my character. It was not easy with Rebecca to say the least, but I think that if you track how she is, if you track her actions they’re always motivated by something internal and obviously not based in reality at all."

3 She Starred In 'Monte Carlo'

Leighton Meester, Selena Gomez, Katie Cassidy, Monte Carlo
via Vogue

Leighton got the opportunity of starring in the teen movie Monte Carlo alongside Selena Gomez and her castmate from Gossip Girl Katie Cassidy. She portrayed Meg Kelly, Selena's character's stepsister, and along with their friend they pose as socialites to infiltrate high society.

"Meg recently lost her mother, and is still a bit traumatised over it. She's somewhat excited to visit France, but not under these circumstances, and certainly not with these two girls," Leighton explained about her character.

2 She Was In The Broadway Show 'Of Mice And Men'

Leighton Meester, Broadway
via Youtube

In 2014, Leighton Meester made her Broadway debut alongside James Franco and Chris O'Dowd for the adaptation of John Steinbeck's novel Of Mice and Men. It was an unforgettable experience for her, and she said it was "everything I wanted it to be."

"I'm so lucky that I got to do (the show) with amazing people who are supportive, and warm, and kind, and friendly, and sensitive." Added Meester, "I'm humbled and thrilled to be part of it."

1 She Starred In 'Life Partners'

Leighton Meester, Life Partners
via Collider

In the movie Life Partners, Leighton played Sasha, a receptionist/musician who becomes very close with Paige, a very conventional environmental lawyer. Sasha is a lesbian while Paige is straight, and that complicates their relationship when Paige starts dating.

"I see very few female roles that come my way that are strong, defined, or independent of male storylines," Leighton explained. "This movie is about women and their friendship, lives, and careers – things that interest them other than dating, guys, love, and sex. My character is the type that speaks to all kinds of women and is characteristic of what I hope to keep doing."

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