Michelle Trachtenberg's Co-Stars Pay Tribute in the Wake of Her Death

In the wake of the tragic news that Michelle Trachtenberg has died at the age of 39, a number of her former co-stars have taken to social media to pay tribute to both her work as an actor and the impact her friendship had on their lives.

Police confirmed on Wednesday that Trachtenberg had been found dead by her mother in her New York City apartment just after 8 a.m. local time. She reportedly recently underwent a liver transplant and may have been experiencing complications. No criminality is suspected.

Trachtenberg was best known in her younger years for her breakout as the titular preteen lead in the 1996 movie adaptation of Louise Fitzhugh's children's novel Harriet the Spy as well as stints on the Nickelodeon sitcom The Adventures of Pete & Pete and the soap opera All My Children. She later went on to play Dawn Summers, the younger sister of Sarah Michelle Gellar's Buffy on Buffy the Vampire Slayer, and chaos queen Georgina Sparks in the original Gossip Girl series—a role she reprised in the 2021 HBO Max reboot in what would be her final performance. Some of her other credits include the 2004 teen sex comedy Eurotrip, 2005 figure-skating movie Ice Princess, and 2009 comedy 17 Again.

As Wednesday afternoon wore on, many of Trachtenberg's castmates shared their memories of her and offered condolences to her friends and family.

Kim Cattrall, who starred in Ice Princess with Trachtenberg, took to Instagram, writing, "Rest in peace sweet Michelle."

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David Boreanaz, who played Angel on Buffy, shared on his Instagram stories: "So very sad...horrible news. RIP and prayers to her and her family."

David Boreanaz, who played Angel on Buffy, shared on his Instagram stories: "So very sad...horrible news. RIP and prayers to her and her family."

Another Buffy colleague, James Marsters, paid tribute to his former costar on Instagram, writing, "My heart is heavy today. We have lost a beautiful soul. Michelle was fiercely intelligent, howlingly funny, and a very talented person. She died much too young, and leaves behind scores of people who knew and loved her. My heart goes out to her family who are good people, and are suffering the greatest loss anyone could bear. I hope everyone can give them space to heal in this most difficult time. Godspeed Michelle. You are missed."

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Blake Lively, who was Serena to Trachtenberg's Georgina on Gossip Girl, wrote a lengthy remembrance on Instagram stories Wednesday evening. “This is the first day I met Michelle,” she wrote on top of a photo of them together. “She was electricity. You knew when she entered a room because the vibration changed. Everything she did, she did 200%. She laughed the fullest at someone’s joke, she faced authority head on when she felt something was wrong, she cared deeply about her work, she was proud to be a part of this community and industry as painful as it could be sometimes, she was fiercely loyal to her friends and brave for those she loved, she was big and bold and distinctly herself." She continued later in the post, "Time passes. You take for granted that you get the chance to see an old friend," urging followers to "hold those you love and have loved dear."

Ed Westwick, who also starred alongside Trachtenberg on Gossip Girl, wrote on Instagram, "So sad to hear of the passing of Michelle Trachtenberg. Sending prayers."

Rosie O'Donnell starred in Harriet the Spy with Trachtenberg in 1996. She told Us Weekly the death was "heartbreaking" for her. "I loved her very much. She struggled the last few years. I wish I could have helped.”

Melissa Gilbert appeared in another 1996 film, A Holiday for Love, with Trachtenberg. Gilbert wrote in a tribute on Instagram, "Oh Michy…and we lived so close to one another…..my heart aches for your family and all those who loved you so…"

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SNL's Kenan Thompson shared, "Our first Nick movie star has departed us!! She was my friend and now she rests!! Check on your people!!!"

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Write to Megan McCluskey at megan.mccluskey@time.com.