Michelle Trachtenberg's death Wednesday left her former co-stars like Blake Lively, Rosie O'Donnell, Melissa Gilbert and Kenan Thompson shocked and saddened.

Blake Lively broke her social media silence on Wednesday to pay tribute to her late “Gossip Girl” co-star Michelle Trachtenberg, who died Wednesday morning at 39. In an Instagram Story, Lively remembered Trachtenberg as a “fiercly loyal” and “kind person, through and through.”