Dr. Will Halstead left Chicago Med at the end of Season 8 after deliberately tampering with an AI-assisted operating room (OR 2.0) to reveal the system's dangerous flaws, which had already caused a patient's death. Aware that someone would have to take responsibility, Halstead submitted his resignation to protect others and close the matter. After leaving Gaffney Chicago Medical Center, he moved to Seattle to reunite with his longtime on-off love, Dr. Natalie Manning. The actor Nick Gehlfuss, who plays Halstead, explained that he left the show because he felt he had taken the character as far as he could creatively and wanted to explore new acting opportunities. Gehlfuss also left the door open for Halstead's potential return to the show, which actually happened in Season 11.
