Michelle Christine Trachtenberg (/ˈtræktənbɜːrɡ/; born October 11, 1985) is an American actress and model. She is known for playing Jenny in EuroTrip (2004), Nona Mecklenberg in The Adventures of Pete & Pete (1994–1996), Dawn Summers in Buffy the Vampire Slayer (2000–2003), Harriet M. Welsch in Harriet the Spy (1996), & Georgina Sparks in Gossip Girl (2008–2012).