Michelle Christine Trachtenberg (born October 11, 1985) is an American actress. Beginning her career as a child, at the age of three, her acting debut was on Nickelodeon television series The Adventures of Pete & Pete (1994–1996). As a child actress, Trachtenberg starred on multiple Nickelodeon productions. In 1997, she won a Young Artist Awards for her performance as Maggie in CBS' Meego. In her early twenties, Trachtenberg rose to prominence in cult classic EuroTrip (2004) and as Georgina Sparks on the CW TV show Gossip Girl, which ran from 2007 to 2012.
Trachtenberg found further success on the WB/UPN supernatural drama television series Buffy the Vampire Slayer (2000–2003) as Dawn Summers, the younger sister of the show's eponymous protagonist, a role which won her another Young Artist Award and earned her three Saturn Award nominations. She also earned a Daytime Emmy Award nomination for her role as the host of the Discovery Kids series Truth or Scare (2001–2003). During the mid-2000s, she had starring roles in the films EuroTrip (2004) and Ice Princess (2005) and supporting roles in the films Mysterious Skin (2004) and Black Christmas (2006). In the late 2000s and early 2010s, her recurring role on the CW teen drama television series Gossip Girl (2008–2012) as socialite Georgina Sparks earned her further popularity, and she also starred on the NBC television series Mercy (2009–2010) as Chloe Payne.
In the 2010s, Trachtenberg starred in several television films, including Killing Kennedy (2013) and Sister Cities (2015), and in the science fiction film The Scribbler (2014). She provided the lead voice of Judy in the Facebook Watch adult animated web series Human Kind Of (2018) and executive produced the teen drama web series Guidance (2015–2017) and the Tubi true crime television series Meet, Marry, Murder (2021).