Michelle Trachtenberg​'s "Buffy the Vampire Slayer" co-star Sarah Michelle Gellar, others react to her death

Former cast members of "Buffy the Vampire Slayer," "Gossip Girl" and more are remembering their co-star Michelle Trachtenberg after the news of her death on Wednesday.

Trachtenberg, 39, was found unresponsive at her home in Manhattan on Wednesday morning, the New York City Police Department said. Criminality is not suspected, they said. 

Trachtenberg began her acting career as a child. At just 11 years old, she landed her breakout role as Harriet in the 1996 movie "Harriet the Spy."