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.

They’ll always be the Summers sisters. Sarah Michelle Gellar and Michelle Trachtenberg became close friends while playing Buffy and Dawn Summers, respectively, on “Buffy the Vampire Slayer” — a tight bond that lasted until Trachtenberg’s tragic death at age 39.

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

Actor Sarah Michelle Gellar paid tribute to her “Buffy the Vampire Slayer” costar Michelle Trachtenberg on Thursday, a day after police foung the 39-year-old dead in her New York City home. Gellar posted a series of old photos on Instagram,

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, Taylor Momsen and Blake Lively are among those paying tribute to Michelle Trachtenberg, who died Wednesday.

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

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.

Sarah Michelle Gellar is remembering her late friend Shannen Doherty while also mourning the death of Michelle Trachtenberg. Gellar, 47, took to Instagram on Thursday, February 27, to pay tribute to Trachtenberg,