Home New York City, NY – Michelle Trachtenberg, known for her roles in “Gossip Girl” and “Buffy the Vampire Slayer,” has died at age 39. Credit: MediaPunch / BACKGRID New York City, NY - Michelle Trachtenberg, known for her roles in "Gossip Girl" and "Buffy the Vampire Slayer," has died at age 39. Credit: MediaPunch / BACKGRID

New York City, NY – Michelle Trachtenberg, known for her roles in “Gossip Girl” and “Buffy the Vampire Slayer,” has died at age 39. Credit: MediaPunch / BACKGRID

LOS ANGELES, CA – OCTOBER 23: Michelle Trachtenberg attends the Third Annual “InStyle Awards” presented by InStyle at The Getty Center on October 23, 2017 in Los Angeles, California. (Photo by Matt Winkelmeyer/Getty Images for InStyle)

Michelle Trachtenberg during World Premiere of “Good Burger” at Paramount Theatre in Hollywood, California, United States. (Photo by Ron Galella/Ron Galella Collection via Getty Images)