Michelle Trachtenberg was found in her New York City apartment, and the death is not believed to be suspicious, police said.

Michelle Trachtenberg, star of “Buffy the Vampire Slayer” and “Harriet the Spy,” has passed away at age 39, according to the New York Police Department. The cause of death was not immediately disclosed,

Trachtenberg starred in 28 episodes of “Gossip Girl” as Georgina Sparks, a recurring character and frenemy of Lively’s Serena van der Woodsen. Georgina, also a member of the Upper East Side’s high society, was notoriously rebellious and known for getting herself and those around her into trouble.

The NYPD said no criminal involvement is suspected and the investigation is ongoing. Michelle Trachtenberg found dead:'Gossip Girl' and 'Harriet the Spy' actress was 39 Gary Mantoosh ...

Trachtenberg starred in a variety of kid-oriented movies and shows, making her film debut in 1996’s “Harriet the Spy.”

Lively was not the only castmember of the beloved teen drama to honor Trachtenberg, who was also known for roles in Buffy the Vampire Slayer and Harriet the Spy. Other Gossip Girl stars including Ed Westwick and Chace Crawford also reacted to her death on social media.

Trachtenberg was 39. Police found her “unconscious and unresponsive” in a Manhattan apartment on Wednesday morning.

Michelle Trachtenberg's memorable movie and TV roles, including 'Gossip Girl' and 'Buffy' Michelle Trachtenberg, who found fame as a child star, became beloved 'Gossip Girl' actre

Michelle Trachtenberg, the actor best known for "Gossip Girl," "Ice Princess" and "Buffy the Vampire Slayer," died at age 39.

Trachtenberg starred in a number of children's movies before getting a breakout role as Dawn in "Buffy the Vampire Slayer."

Michelle Trachtenberg, star of film and television projects like 'Gossip Girl' and 'EuroTrip,' has died at the age of 39, Deadline has confirmed.

Police responded to a 911 call early Wednesday morning at a residential tower in midtown New York City where “officers observed a 39-year-old female unconscious and unresponsive,” according to an NYPD statement.