Most well-known for her spirited role as Anna Stern on The O.C., Armstrong brought along a similar sass to her memorable role as Jeremy Piven's assistant on HBO's Entourage. Film-wise, Armstrong quietly wowed audiences in Not Another Teen Movie and Stay Alive, but don't be surprised if she steals the coveted spotlight from Lindsay Lohan, her costar in Just My Luck.

1. Her name means Dawning Sun in Gaelic. Her nickname is Sasa.
2. She has her own fashion label called NARU.
3. She trained in sword practicing and judo while living in Japan. She later moved to Hawaii, then Arizona.
4. She loves Mary-Kate and Ashley Olsen.
5. For a year, she majored in Costume Design and Theater at the University of Arizona.

On partying: "I save my craziness for a New Year's or a Fourth of July and everyone is in anticipation because they know what's about to happen. The end of the night is the worst. I always end up by the toilet."