AceShowbiz - The entertainment industry is in deep mourning following the sudden passing of beloved actress Michelle Trachtenberg, best known for her roles in "Buffy the Vampire Slayer" and "Gossip Girl." The actress passed away at the age of 39, and her co-stars and friends have taken to social media to pay their heartfelt tributes.

Trachtenberg, a beloved figure of '90s and 2000s teen culture, was found unresponsive by her mother in her Manhattan apartment at around 8 a.m. on Wednesday, February 26. While the exact cause of death has not been disclosed, sources believe complications from a recent liver transplant might have played a role.

"It is with great sadness to confirm that Michelle Trachtenberg has passed away. The family requests privacy for their loss. There are no further details at this time," her representative told various outlets.

Known for her infectious energy and undeniable talent, Trachtenberg left an indelible mark on everyone she worked with. Ed Westwick, her co-star from "Gossip Girl," shared, "So sad to hear of the passing of @michelletrachtenberg," adding, "sending prayers." Kim Cattrall, who worked with Trachtenberg on "Ice Princess," also paid tribute, saying, "Rest in peace sweet Michelle."

Alyson Hannigan, her "Buffy the Vampire Slayer" co-star, shared, "I am deeply saddened by the news of Michelle's passing. She brought a loving energy to the set of Buffy."

Meanwhile, James Marsters, who played Spike, poignantly noted, "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."

Trachtenberg's journey in Hollywood began as a child star. She captured hearts alongside Rosie O'Donnell in the 1996 film "Harriet the Spy." Reflecting on their time together, O'Donnell remarked, "I loved her very much. She struggled the last few years. I wish I could have helped."

Other notable tributes came from long-time colleagues and co-stars. "Saturday Night Live" star Kenan Thompson, who starred with Trachtenberg on Nickelodeon, posted, "Our first Nick movie star has departed us!! She was my friend and now she rests!!"

Blake Lively, who featured alongside Trachtenberg in "Gossip Girl," reminisced, "She was electricity. She was fiercely loyal to her friends and brave for those she loved."

As the tributes pour in, Hollywood remembers Michelle Trachtenberg not just for her memorable roles but for the vibrant, kind, and loyal person she was. Her passing is a poignant reminder to cherish those who bring light into our lives, and her legacy will undoubtedly continue to inspire many.