Before The OC came along, Mischa was a child actress and model.
You can glimpse her in classic romantic comedy Notting Hill, or even more memorably...
She also played the ghost girl vomiting on herself in The Sixth Sense. Amazing that she was known as one of the most beautiful girls in Hollywood after that one!
She had a recurring role on TV on the ABC drama Once and Again in which she played the lesbian love interest for Evan Rachel Wood's character.
Mischa was also the voice of cartoon character Betty Ann Bongo on the mid 90s Nick show Kablam!.
She had other small TV roles on All My Children and Fastlane.
Mischa was later known as a total style star, but it's hard to believe now due to the horror that was mid 00s fashion!
When The OC premiered in August 2003, Mischa was just 17 years old, about the same age as her character.
Mischa played Marissa Cooper, the prettiest girl in school who also has a bit of a drinking problem.
The show was an overnight smash success.
The cast of Mischa, Adam Brody, Ben McKenzie, and Rachel Bilson became instant A-listers.
Mischa picked up endorsements for wholesome brands like Neutrogena skincare and Keds shoes.
Entertainment Weekly named her their It Girl of 2003.
She appeared on tons of magazine covers and hit many red carpets at events.
How amazing was 2003! Mischa was on top of the world, and Jessica Simpson and Nick Lachey were still together.
Mischa got some negative press attention for looking a bit too skinny, followed eventually by attention for gaining too much weight.
At the height of her OC fame, Mischa dated socialite and oil heir Brandon Davis, who is best known as the guy who made fun of Lindsay Lohan with his pal Paris Hilton.
Mischa's character was killed off The OC in the finale of season three. Many believe the show jumped the shark with that moment, and the show was canceled after the next season.
Mischa dated Cisco Adler in 2007, a rocker bad boy who had also dated party girl Kimberly Stewart. They broke up after a nude photo of Cisco made its way around the Internet.
A few months later, in December 2007, Mischa was arrested for suspicion of driving under the influence and driving without a license.
Mischa now says her parents attempted an intervention in 2009, then placed her on a 5150 hold in a psychiatric ward after she blacked out under the influence of sedatives.
She's most recently dated actor Sebastian Knapp, but the two parted ways in August 2013.
Mischa seems to be back on the right track. She has a new movie out soon, a TV pilot in the works, and has opened clothing and beauty boutique in London.