Michelle Trachtenberg, the actor known for roles in series including “Buffy the Vampire Slayer” and “Gossip Girl,” has died, according to US media outlets. She was 39 years old.

Police said officers responded to an emergency call just after 8:00 am local time (1300 GMT) on Wednesday, The New York Times said, where they found her in her Manhattan apartment unconscious and unresponsive.

Emergency medical workers pronounced her dead without giving a cause. Police said foul play was not suspected.

Citing anonymous sources, ABC News reported that the actor recently underwent a liver transplant, and was perhaps experiencing complications.

New York native Trachtenberg began her career as a child star, with roles including the titular character in the 1996 film “Harriet The Spy,” which she played alongside Rosie O’Donnell.

She also had credits on the Nickelodeon kids network, including on the television series “The Adventure of Pete & Pete.”

Her big break came on “Buffy the Vampire Slayer,” where she played Dawn, the younger sister of Sarah Michelle Gellar’s leading character.

She acted on that show from 2000 to 2003.

Trachtenberg later starred as the socialite villain Georgina Sparks on the hit show “Gossip Girl” from 2008 to 2012, with co-stars including Blake Lively, Penn Badgley and Leighton Meester.

Her other film roles included “EuroTrip,” “17 Again” and “The Scribbler.”

Trachtenberg made a number of cameos on television shows including “Weeds” and “Mercy,” appearing in the Gossip Girl reboot in 2022, what’s listed as her final acting credit.

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