In June 2023, the Chicago One family mourned the death of Treat Williams. The 71-year-old actor was riding a motorcycle in Dorset, Vermont, when he was struck by a car. He suffered traumatic injuries and was rushed to Albany Medical Center in New York, where he was pronounced dead. The motorist who crashed into Williams, Ryan Koss, was charged with “grossly negligent operation with death resulting.” As reported by NBC5, Koss pleaded not guilty to the charge in September 2023.

During Season 2 of “Chicago Fire,” Williams joined the cast in a recurring role as Benny Severide, the father of Taylor Kinney’s character Kelly Severide. Benny was killed off during Season 7, but Williams left a lasting impression on his former castmates. In a statement to People, Kinney said of Williams’ tragic death, “He played my father on Chicago Fire, and was a father figure to everyone on set. I’ll always relish our conversations and his uncanny ability to light up a room. We all send love, he will be missed.” 

Kim Delaney, who played Benny’s ex-wife on the show, also paid tribute to the actor. “Sooo sad,” she captioned an Instagram photo of herself and Williams smiling outside Carmine’s restaurant in Chicago. “Amazing, kind man always. Condolences to all his family.” Williams was also known for his roles in “Everwood” and “Hair,” and he’s among the many “Blue Bloods” stars whose deaths have saddened fans of the procedural.