Awful news today (via Variety):

She was found unconscious and unresponsive Wednesday in her Manhattan apartment, according to the New York City police department. According to the New York Post, which first reported the news, she had recently undergone a liver transplant. Trachtenberg’s cause of death has not been confirmed, but the NYPD said criminality was not suspected.

I’m heartbroken. I loved her in Buffy the Vampire Slayer. She was a crucial part of what made Season 5 special. She was the perfect “annoying little sister” while remaining deeply charming and lovable. Her introduction in that season may be the most successful execution of a Cousin Oliver. Like many fans, I consider the season to be one of the show’s strongest, due in large part to her character and her ebullient performance. Perhaps because of that character, I’ve always felt she was an old soul. At 39, she’s left us far too soon.

Tributes are starting to pour in from her coworkers, and they’re agonizing.