Michelle Trachtenberg is joining the cast of Gossip Girl.

The former Buffy the Vampire Slayer and EuroTrip star will portray Georgina Sparks, a troublemaker from Serena's (Blake Lively) past. As earlier reported, thin actress Mischa Barton had been offered the role.

This marks the second big project for Trachtenberg in 2008. She's also starring alongside Zac Efron in the movie 17 Again, out in August.