"She struggled the last few years"— Michelle Trachtenberg's co-star from Harriet the Spy Rosie O'Donnell and others mourn her passing

After the news of Michelle Trachtenberg's death at 39 on Wednesday, February 26, 2025, there has been an outpouring of tributes from her fans, friends, and former co-stars. Rosie O'Donnell, who worked with the late actress in Harriet the Spy, was among one of the first to share a heartfelt message upon hearing what happened to Trachtenberg.

Sharing a statement to People, O'Donnell said that hearing her former co-star's passing was heartbreaking. The Irish-American comedian and actress also referenced Trachtenberg's struggles, saying:

"I loved her very much. She struggled the last few years. I wish I could have helped."

Harriet the Spy marked Michelle Trachtenberg's big-screen debut. She played the titular role, a sixth-grader spy, alongside O'Donnell's Ole Golly, her beloved nanny.

Per The New York Post, Trachtenberg passed away on Wednesday morning after experiencing cardiac arrest. However, when the paramedics arrived at the Gossip Girl star's home in Manhattan, she was already "unconscious and unresponsive."

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More Harriet the Spy and Buffy The Vampire Slayer co-stars shared tribute to Michelle Trachtenberg amid her passing

Besides O'Donnell, another Harriet the Spy co-star, J. Smith-Cameron, who played Michelle Trachtenber's fictional mother in the movie, shared a statement following her death. She recalled working with the late actress in the film in a statement via People, saying:

"Michelle had been on a Nickelodeon show called Adventures of Pete & Pete but this seemed to be her first lead film role. She was so excited. Her natural ebullient nature was ratcheted up into giddiness as she tried to learn how to handle all that came with that."

Smith-Cameron recalled Michelle Trachtenberg as a "very charming little girl." She said that they reconnected briefly on social media years after the movie and remembered how the late actress was "always very warm" towards her.

Michelle Trachtenberg's Buffy the Vampire Slayer co-stars were also shocked by her passing. While she wasn't part of the original cast, she joined the series in its fifth season as Dawn Summers, Sarah Michelle Gellar's Buffy Summer's little sister. She stayed in the show until it ended in 2003 after seven seasons. Alyson Hannigan, who played the witch Willow Rosenberg in the series, shared a tribute to her former co-star on Instagram.

Alongside throwback photos of her and Trachtenberg over the years, including set photos from Buffy the Vampire Slayer, she wrote:

"I am deeply saddened by the news of Michelle's passing. She brought a loving energy to the set of Buffy. My thoughts are with Michelle's family and friends."

James Masters, aka Buffy's vampire Spike, who shared countless scenes with Michelle Trachtenberg's Dawn, recalled the late actress as a "fiercely intelligent, howlingly funny, and a very talented person" in a statement to People.

The show's vampire Angel, David Boreanaz, also wrote on his Instagram Story about the "horrible news" of the actress' passing. Emma Caulfield, who was the former demon Anya Jenkins in the series, also took to her Instagram story to share a tribute to the Buffy family's "little sister."

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While it remains unknown as to what caused her death, it was not deemed suspicious. The NY Post also reported that she underwent a liver transplant sometime in 2024, and cited sources suggesting that she may have had complications from it.