She passed away yesterday morning at age 39. Possibly from complications of a recent liver transplant.
https://apnews.com/article/michelle-trachtenberg-dead-1789e0979c1548e4e56760badfad73ee
I posted my first watch-through of Buffy at the other place. Like many others, I wasn't sure what to think about Dawn at first, but Michelle's passion for the role won me over.
Condolences to her family, friends, and fans.