The O.C. Cast: Then and Now
Rachel Bilson: Then
Bilson's Summer Roberts was originally intended to appear in just a few episodes, but the actress charmed audiences and was soon upgraded to series regular. Throughout the show's four seasons, her character was involved in an on-and-off relationship with the adorkable Seth Cohen (Adam Brody, whom she also dated in real life). In the series finale, Summer and Seth tied the knot.