Sarah Michelle Gellar is remembering her friend and TV “sister” Michelle Trachtenberg after the actress’s tragic death at age 39 on Feb. 26. Gellar posted a moving tribute to her Buffy the Vampire Slayer co-star on Instagram, including a sweet throwback photo of Trachtenberg with Gellar’s daughter Charlotte, now 15, as a baby. Grab the …

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

The actress, who died at age 39, made her feature debut in the 1996 movie, with filmmaker Bronwen Hughes telling The Hollywood Reporter, "She never had a false note."

Michelle Trachtenberg, a former child star who appeared in the 1996 “Harriet the Spy” hit movie and went on to co-star in two buzzy millennial-era TV shows — “Buffy the Vampire Slayer” and “Gossip Girl” — has died.

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

O’Donnell and Trachtenberg appeared together in the 1996 film “Harriet the Spy,” the late actor’s first leading role.

Fans mourning the loss of Michelle Trachtenberg following her death Wednesday at the age of 39 are revisiting some of her most beloved works, among them, Harriet the Spy. Before the actress became known as Dawn Summers on Buffy the Vampire Slayer and Georgina Sparks on Gossip Girl,

Michelle Trachtenberg, an actress who starred in “Gossip Girl” and “Harriet the Spy,” was found dead in her luxury Midtown Manhattan apartment early Wednesday, police sources said. Trachtenberg, 39, was found unresponsive by her mother in her apartment near Columbus Circle at 8 a.m.

Michelle Trachtenberg has died at the age of 39, but her vast library of TV and film roles continue to live on. (Mark Mainz/AP)

Michelle Trachtenberg at the premiere of "Harriet the Spy" July 9, 1996 in New York City. (Ron Galella/Ron Galella Collection via Getty Images) But for other households, that wasn’t the case.

Michelle Trachtenberg, the actress known for 'Harriet the Spy,' as well as TV shows like 'Buffy the Vampire Slayer' and 'Gossip Girl,' has died.

By Ryan Gajewski Senior Entertainment Reporter “Michelle ... set of Harriet the Spy. Courtesy of Everett Collection Among other notable industry figures to have reacted publicly to Trachtenberg ...