Nicholas Brendon, Alyson Hannigan, Charisma Carpenter, and others also paid tribute to their former costar after her tragic passing on Feb. 26.

Blake Lively, Sarah Michelle Gellar, David Boreanaz, Ed Westwick, Kim Cattrall, Kenan Thompson, Melissa Joan Hart and more shared tributes to Trachtenberg.

Nearly 30 years after starring in Harriet the Spy with Trachtenberg, Rosie O’Donnell mourned her passing in a statement to Us Weekly. “Heartbreaking,” she said. “I loved her very much. She struggled the last few years. I wish I could have helped.”