Michelle Christine Trachtenberg / tr kt nb r '/ is an American actress. She is known for portraying Nona F. Mecklenberg on The Adventures of Pete & Pete, Dawn Summers on Buffy the Vampire Slayer, and Georgina Sparks on Gossip Girl. She has also appeared in films such as Harriet the Spy (1996), EuroTrip (2004), Ice Princess (2005), Black Christmas (2006), and 17 Again (2009).