Michelle Trachtenberg arrives at the premiere "10,000 B.C." on March 5, 2008 in Hollywood, California.
Jon Kopaloff/FilmMagic

Hey there, Upper East Siders: Michelle Trachtenberg is joining the cast of Gossip Girl and she's ready to be a "bitch."

"I am super excited," the former Buffy the Vampire Slayer star told Usmagazine.com at the Prada Trembled Blossoms party in Beverly Hills last night. "[Creator] Josh Schwartz is an awesome dude and he is inspiring me to bring out my inner bitch!"

Trachtenberg, 22, begins shooting next week and will appear in four episodes, a source on the show confirms to Us.

Her character? Georgina Sparks, an old friend of reformed party girl Serena van der Woodsen (Blake Lively).

(Mischa Barton had also been approached for the guest spot, but turned it down — as Us first reported.)

Trachtenberg says it's a role she knows well.

"I got to play a bitch when I did Six Feet Under and it was super fun, and I think this show is young and is so on tap with what’s going on today," she said.

New episodes of Gossip Girl return April 21.

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