Season four wraps up with an explosive finale, including the return of Georgina Sparks and Constance Billard mean girls Kati and Is, a cameo by "Gossip Girl" author Cecily von Ziegesar, a performance by Airborne Toxic Event and, oh yeah, a few very juicy cliffhangers. Watch free, streaming full episodes of Gossip Girl on cwtv.com. Gossip Girl Video: Watch Gossip Girl full episodes, previews, clips, interviews and more video. Gossip Girl is based on the best-selling series of young-adult novels by Cecily von Ziegesar and executive produced by Josh Schwartz and Stephanie Savage. Gossip Girl is a drama based on the lives of privileged Manhattan prep school teens.