Adam Brody and Rachel Bilson of The O.C.
Character names: Seth Cohen & Summer Roberts
Years dated in real life: 4
Adam Brody and Rachel Bilson's real life romance lasted just about as long as their series, The O.C. It began with nerdy Seth pining after the uber-popular Summer, his childhood crush, and it ended with the two getting married in a flash forward sequence on the show's series finale.