Exactly 15 years ago, Mischa Barton's departure from the hit Fox drama "The O.C." dealt a devastating blow to fans. Her character, Marissa Cooper, was killed in the third season finale, leaving behind a superstar-sized hole in the show's storyline.

In which episode does Marissa die?

Marissa was part of The Core Four, until her death, which took place in the final of the third season, entitled : "The Graduates".

Why did they kill Marissa off the OC?

In the show's second season, Barton says shooting became more strenuous, and she didn't see a clear path for her character, Marissa. ... Barton said she was turning down leading roles in big films due to her work on the series, and finally decided to step away from The O.C. to pursue those opportunities.