Chicago Fire will say goodbye to one of its longest-serving stars after 12 seasons. The NBC flagship show is the first installment in the One Chicago franchise, which also comprises Chicago P.D., Chicago Med, and the previously cancelled Chicago Justice. Fire focuses on the personal and professional lives of the firefighters in the fictional Firehouse 51 and has so far run for a total of 249 episodes. Chicago Fire
season 12 is approaching its conclusion, and over the course of its run, it has already seen a number of cast changes. 
