Trachtenberg, who co-starred with Gellar on the hit TV series, was found dead in her apartment on Tuesday. She was 39.

Gellar is honoring her late 'Buffy the Vampire Slayer' costar, who died on Wednesday, February 26, with a powerful quote from the show.

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