A cause of death has not been disclosed. Westwick, who played Chuck Bass in "Gossip Girl" opposite Trachtenberg's Georgina Sparks, mourned his former co-star by sharing a photo of her on his Instagram Story.

Kenan Thompson shared a touching tribute to his fellow Nickelodeon alum Michelle Trachtenberg, who died at age 39 on Wednesday, Feb. 26.

Rosie O'Donnell, Ed Westwick, SAG-AFTRA and others react to the 39-year-old's passing The post Michelle Trachtenberg’s Former Co-Stars Heartbroken Over Her Death: ‘I Wish I Could Have Helped’ appeared first on TheWrap.