Actress Michelle Trachtenberg, 39, was found dead in her apartment in February. Authorities initially listed her cause of death as undetermined, but have now officially ruled it complications from diabetes. The initial belief was that her death stemmed from liver surgery complications. Following the announcement, several former co-stars, including Blake Lively and Rosie O'Donnell, shared heartfelt tributes.

Prepared by Emily Rhodes and reviewed by editorial team.