Michelle Trachtenberg’s former “Buffy the Vampire Slayer” costar Sarah Michelle Gellar is looking back at their time together on screen and off, one day after Trachtenberg died in New York City.

Sarah Michelle Gellar and Michelle Trachtenberg starred in three seasons of "Buffy the Vampire Slayer" together and remained close following the end of the series.

Sarah Michelle Gellar is paying tribute to her late "Buffy the Vampire Slayer" co-star Michelle Trachtenberg after her tragic death at age 39.

Sarah Michelle Gellar, Taylor Momsen and Blake Lively are among those paying tribute to Michelle Trachtenberg, who died Wednesday. Trachtenberg was found in her New York apartment “unconscious and unresponsive,

Several actors, including Blake Lively and Melissa Joan Hart, have paid tribute to Trachtenberg after she died on Wednesday.

Sarah Michelle Gellar has paid tribute to her former Buffy The Vampire Slayer co-star Michelle Trachtenberg following her death Wednesday at 39.

Sarah Michelle Gellar is mourning the loss of Michelle Trachtenberg. On Thursday, Feb. 27, the day after the actress was found dead at 39 in her apartment, Gellar, 47, paid tribute to her with a carousel of photos from their time on Buffy the Vampire Slayer together.

Michelle Trachtenberg's death at age 39 hit her legion of fans quite hard on Wednesday, and her onscreen sister from "Buffy the Vampire Slayer" was no different. Sarah Michelle Gellar quoted her iconic character in her tribute to the actress behind little sister Dawn on Thursday.

Sarah Michelle Gellar mourned the death of “Buffy the Vampire Slayer" co-star Michelle Trachtenberg in an Instagram post.