Michelle Trachtenberg

Michelle Trachtenberg will guest-star on NCIS: LA, TVGuide.com has confirmed.

The Gossip Girl and Buffy the Vampire Slayer alum will play Lily, a charming and physically capable environmentalist and private chef. When a scary home invasion turns her life upside down, she does her best to show a brave face, despite dangerous and uncertain circumstances.

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Trachtenberg, who recently appeared in Killing Kennedy, will appear in a holiday-themed episode slated to air Tuesday, Dec. 17 at 9/8c on CBS.

(Full disclosure: TVGuide.com is owned by CBS.)