She is portrayed by Alice Callahan.
Jessica is not a part of the Gossip Girl series of books.
Jessica makes her first appearance in The Empire Strikes Jack, when she meets Blair at Eleanor Waldorf's fashion show. She expresses great admiration for Blair, especially after following her life on Gossip Girl. In It's a Dad, Dad, Dad, Dad World, Jessica and her friend Zoe run into Blair on the Columbia campus. Blair lies that she is transferring there but is eventually outed in a Gossip Girl blast. After this, Jessica and Zoe ignore her until Blair reveals that she is indeed attending Columbia the next fall, after Chuck Bass applied for her. She then hires the two girls as her new minions
In The Undergraduates, the new school year at Columbia starts and it's revealed that Jessica is a member of Hamilton House; along with Blair, Serena van der Woodsen, Juliet Sharp, and Penelope Shafai. Throughout the season, she works for Blair as a minion.
Jessica remains employed by Blair, and appears as a bridesmaid in G.G. when Blair marries Prince Louis Grimaldi. In the season finale The Return of the Ring, Jessica misunderstands that Blair calls her thickheaded but gets over it quickly.
In High Infidelity, Jessica and Kati Farkas break into Poppy Lifton's atelier to find out how similar her dresses are to Blair's. In Monstrous Ball, Blair initially sets Jessica to attend Cotillion and wear one of her dresses but changes her mind after she makes a deal with Sage Spence to wear it instead. This is Jessica's last appearance in the show.