Michelle Trachtenberg's cause of death was revealed Thursday after the 39-year-old actress was found dead in New York City Wednesday morning.

The 'Gossip Girl' star passed away in February 2025 at age 39, and her former cast members are reacting to the devastating loss.

The "Gossip Girl" and "Harriet the Spy" alum, who rose to fame as a child star, was found dead in New York City on Wednesday, according to police.

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

Blake Lively, Sarah Michelle Gellar and other stars remembered Trachtenberg’s work ethic and friendship in social media posts.

Hollywood is mourning actress Michelle Trachtenberg, who died on Wednesday. She was 39. Trachtenberg, best known for roles in "Buffy the Vampire Slayer," "Gossip Girl," Disney's "Ice Princess" and more, is believed to have died of natural causes, police sources told ABC News.

Michelle Trachtenberg, an actress best known for her roles in "Buffy the Vampire Slayer" and "Gossip Girl," has died at age 39.