Penn Badgley (Dan) and Blake Lively (Serena) had known each other for years prior to the show, as they were home-schooled together when they were child actors.
The CW did not want Ed Westwick to play Chuck Bass, insisting that he looked "more like a serial killer than a romantic lead."
When the show was criticized by the Parent Television Council for being "mind-blowingly inappropriate" and "every parent's nightmare," those exact phrases were used in the show's promotional posters.
The Empire Hotel that Chuck owned is a real hotel. After fans swarmed the hotel, the bar at The Empire started serving Gossip Girl-themed cocktails, including an "XOXO" cocktail with secret ingredients that they'll never tell.