Portrayed by Kelly Rowan, she is the wife of Sandy Cohen, the mother of Seth, adoptive mother of Ryan, and former CFO of her father's (Caleb Nichol) real estate company, the Newport Group.
Before she met Sandy she dated and grew up with Jimmy Cooper father of Marissa Cooper, with whom she remains friends.
Initially Summer was only intended as a small supporting character, only there as an object of fantasy for Seth and a friend for Marissa Cooper, while Ryan Atwood and Marissa were the lead couple.
However, due to Bilson's performance, Summer became an increasingly important character.
He forms fast bonds with the entire Cohen family, especially Sandy's son Seth, as well as an extreme attachment to the girl next door, Marissa Cooper.
She is portrayed as highly sexualised and initially appears stupid; later she undergoes something of a transformation and becomes far more intelligent and concerned about environmental issues, a change possibly due to her relationship with the geeky Seth Cohen.The character's politics and lifestyle are conservative, a contrast to her husband.Kelly Rowan described the character as seemingly more "together" than herself during an interview.He is known for his quick quips, comic book fascination, and pop-culture references.He is also the love interest of Summer Roberts, on whom he had a crush on since third grade.