Mischa Barton as Marissa Cooper
Ah, Marissa Cooper — the troubled girl whose Season 3 death left us locked in our room for days. Before the emotions come flooding back (too late), let's discuss what Mischa did post The O.C. She went on to various projects, including the films Assassination of a High School President (2008) and Homecoming (2009) and the short-lived 2009 series The Beautiful Life. While we'd love to see her back on TV (in something other than TBL), Mischa has been working with the stage, as well. She played Shelby in the 2012 stage production of Steel Magnolias.