Over the years, several actors have left the One Chicago universe for various reasons. Whether it's to pursue new creative avenues, conflicts on or off-screen, or planned character exits to drive the plot, cast changes are inevitable in a long-running series. However, the reputation of One Chicago for recurring cast turnover ensures that new characters are consistently introduced, keeping the drama and entertaining storylines alive.

One Chicago is a collection of interconnected NBC dramas centered around the emergency responders of inner-city Chicago. Created by TV producer Dick Wolf, the franchise began with Chicago Fire in 2012, followed by Chicago P.

D. in 2014, Chicago Med in 2015, and Chicago Justice in 2017. These shows have ambitious interconnected programming, with complex crossovers linking storylines and characters across the three main shows.

One of the recent departures from Chicago Med was Nick Gehlfuss, who portrayed Dr. Will Halstead. After eight seasons, Gehlfuss felt that he had taken the character as far as he could and decided it was time to move on. This decision was kept hidden until the episode aired. Similarly, Jesse Lee Soffer, who played Detective Jay Halstead in Chicago P.D., announced that season 10 would be his last.

Soffer wanted to pursue new opportunities and directed an episode in his final season.

Jesse Spencer, who portrayed Captain Matthew Casey in Chicago Fire, left the show after 10 seasons to seek a change after 18 years of doing television. Yaya DaCosta and Torrey DeVitto also left Chicago Med in 2021 to pursue other acting opportunities. There have been planned departures, like Archie Kao's character Sheldon Jin in Chicago P.D., whose exit was necessary for a cliffhanger plot twist. 

Other actors, such as Sophia Bush, Monica Raymund, and Lauren German, left their respective shows due to personal and behind-the-scenes reasons.

Bush, who played Erin Lindsay in Chicago P.D., left the show due to abusive behavior from producers. Raymund, who portrayed Gabby Dawson in Chicago Fire, left to aid Puerto Rico hurricane relief efforts and seek new roles. German's character Leslie Shay tragically died in Chicago Fire, adding to the show's dramatic impact.

In some cases, the actors' departures were purely for creative reasons. Colin Donnell, who played Dr. Connor Rhodes in Chicago Med, left after the fourth season for unspecified creative reasons. Similarly, original cast member Elias Koteas's character Alvin Olinsky met a tragic end in Chicago P.

D. as part of a storytelling decision. 

Overall, the departures of actors from the One Chicago universe are varied, with reasons ranging from personal choices to creative decisions by the producers. However, the ever-changing cast ensures that the shows continue to introduce new characters and provide audiences with ongoing drama and entertaining storylines.