Over the course of 33 seasons and 662 episodes,One Chicagohas experienced a good number of cast exits, and as for the 2024–2025 TV season,six actors and actresses across the three shows will not be returningto the franchise.TheOne Chicagouniversewas established in October 2012 with the premiere ofChicago Fire, withChicago PDdebuting in January 2014 andChicago Medarriving in November 2017 (a third spinoff,Chicago Justice, was released in March 2017 but was canceled after one season). All three procedural TV series are still going strong, despite their various casting changes.
All threeOne ChicagoTV shows are set to premiere on Wednesday, September 25, on NBC, withChicago Medseason 10 dropping at 8 p.m. ET,Chicago Fireseason 13 at 9 p.m. ET, andChicago PDseason 12 at 10 p.m. ET. Each season is expected to contain 22 episodes.

Heading into the 2024–2025 season,Chicago Fireis in its thirteenth season,Chicago PDis on season 12, andChicago Medhas finally reached double digitswith its tenth season. Given that each show has had long runs (which is quite extraordinary in this day and age of TV), it makes sense why the casts don’t look the same as they did during their pilot episodes. Onlyfour initialChicago Firecast members remain in season 13, whileChicago PDhas five original stars in season 12 andChicago Medhas three in season 10.
6Dominic Rains As Crockett Marcel
Chicago Med
The semi-good news is that only oneChicago Medcast member is exiting ahead of the season 10 premiere; the bad news is that cast member is Dominic Rains. Rains has played Dr. Crockett Marcel, a Fourth Year Resident in General Surgery who was later promoted to Attending Physician in General Surgery at Gaffney Chicago Medical Center, since the season 5 premiere.Chicago Medintroduced Marcel following the exit of Colin Donnell’s Dr. Connor Rhodes,and Rains has been a series regular up until season 10. Sadly,Marcel has exitedChicago Medfollowing the release of the season 9 finale.
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Marcel’s grief concerning the death of his one-year-old daughter resurfaced after he learned that his young patient had died during theChicago Medseason 9 finale.Marcel admitted that he had never properly dealt with his grief,and the episode ended with viewers questioning if he would take some time off from work to process his feelings. However, it seems as though Marcel is taking a permanent vacation from Gaffney. What makesMarcel’sChicago Medexit so disappointingis that the medical drama never gave him proper closure, and now Rains isn’t returning to properly wrap up his character’s story.
5Tracy Spiridakos As Hailey Upton
Chicago PD
Similar toChicago Med, only oneChicago PDseries regular won’t be returning during the 2024–2025 season.Tracy Spiridakos' Detective Hailey Upton said goodbye to the Intelligence Unit and Chicagoduring theChicago PDseason 11 finale, while the audience sadly had to bid Upton farewell. Spiridakos was not a part of the police procedural’s original cast as she came in whenSophia Bush leftChicago PD. However, given Spiridakos' tenure on the show and her character’s importance to the story, it felt like the actress had been around since the beginning. Now, Upton is gone (and probably for good).
Chicago PDintroduced Upton towards the end of season 4,and NBC made Spiridakos a series regular in season 5 following Bush’s exit. Over the course of over seven seasons, Upton made her mark ontheOne ChicagoTV show. She connected with her colleagues in the 21st District and proved her worth as an important addition to the team.
Upton later started dating her partner, Jay Halstead, and the two characters ended up getting married in season 9. Unfortunately, their relationship wasn’t built to last after Halstead rejoined the Army.Upton ultimately divorced Halstead in season 11,which partially contributed toSpiridakos' character quitting and leaving the city at the end of theChicago PDseason 11 finale. So, Upton is not expected to appear in season 12.
4Rome Flynn As Derrick Gibson
Chicago Fire
Even though Rome Flynn’s Derrick Gibson didn’t stick around for too long,the character’sChicago Fireexit in season 12 is still disappointing. The NBC procedural dramaintroduced Gibson during season 12, episode 2,in the wake of Blake Gallo’s exit. Gibson was a floater firefighter previously assigned to Truck 46 who joined Truck 81 after Stella Kidd saw him in action and was impressed. However, Flynn’s character would only be a part of Firehouse 51 for a handful of episodes before leaving.
NBC replaced Gibson with Jack Damon (who was later revealed to be Kelly Severide’s half-brother), so, viewers should expect to see Jack, not Gibson, duringChicago Fire’s 2024–2025 season.
Like many other characters, Gibson and his past were a bit of a mystery at the beginning. It was later revealed that he was a former amateur boxer who accidentally killed someone in the ring, which led to his prescription drug abuse. Sadly, his addiction got out of hand, andGibson left Firehouse 51 to seek treatment duringChicago Fireseason 12, episode 8.NBC replaced Gibson with Jack Damon (who was laterrevealed to be Kelly Severide’s half-brother), so, viewers should expect to see Jack, not Gibson, duringChicago Fire’s 2024–2025 season.
3Alberto Rosende As Blake Gallo
As mentioned above, Blake Gallo, played by Alberto Rosende, alsoexitedChicago Fireduring season 12.Gallo was first seen in season 8, episode 2,following in the wake of the tragic death of Brian “Otis” Zvonecek. Rosende’s character, who was initially assigned to Truck 90, joined Firehouse 51 after Matt Casey saw him climb a building to save someone. Impressed, Casey and Kelly Severide convinced Chief Boden to give Gallo a shot, and the young firefighter became an official member of Truck 81.
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Over the course of Rosende’s four seasons on the NBC procedural drama, his character grew and opened up about his tragic past. Gallo wasn’t exactly lucky in the love department as his fling with Violet Mikami ended before it even truly began, and Joe Cruz constantly got in the way of his relationship with Gianna Mackey. Ultimately,Gallo quit Firehouse 51 to move to Detroit, Michigan, to care for his auntin theChicago Fireseason 12 premiere, meaning Rosende won’t return during the 2024–2025 TV season.
2Kara Killmer As Sylvie Brett
Just like Tracy Spiridakos inChicago PD, Kara Killmer was not an original member of theChicago Firecast as her character,Sylvie Brett, was introduced in season 3 to replace Leslie Shay as a paramedic on Ambulance 61.However, Brett slowly but surely became an integral character on the show, making her exit all the more devastating. Killmer remained a series regular for almost 10 seasons and 200 episodes, and, consequently, Brett’s contribution to the series was invaluable. Nevertheless,Killmer wanted to leaveChicago Fire, and the writers devised a perfect exit for her character.
Casey and Brett’s wedding transpired duringChicago Fireseason 12, episode 6, and the two drove off into the sunset.
FollowingMatt Casey and Gabby Dawson’s breakup inChicago Fire, sparks began to fly between Casey and Brett. However, despite Gabby’s departure from Firehouse 51 and the city, Casey and Brett were hesitant to act on their feelings. But by the season 9 finale, the couple had finally given in to their feelings. Unfortunately, Casey quit and moved to Oregon to take care of Andrew Darden’s two sons during season 10, and Casey and Brett’s relationship couldn’t withstand long distance. When Killmer decided to exit the show, though,the perfect opportunity to make Casey and Brett endgame arose.
Jesse Spencer reprised his role as Casey during the season 11 finale to propose to Brett. Since the episode ended with that cliffhanger, viewers didn’t hear Brett’s answer until the season 12 premiere. But, of course,Brett agreed to marry Caseyand move to Oregon to be with him. So,Casey and Brett’s wedding transpired duringChicago Fireseason 12, episode 6, and the two drove off into the sunset. Unfortunately, that means that neither character will appear inChicago Fireseason 13.
Chicago Fire Season 13’s Boden Replacement Makes Me Very Excited Thanks To Great Casting Choice
NBC has revealed Chief Boden’s replacement in Chicago Fire season 13, and the new cast member is the perfect choice for the procedural series.
1Eamonn Walker As Wallace Boden
One Chicago’s 2024 seasons featured many heartbreaking exits, but none of them could hold a candle toChief Wallace Boden’s departure fromChicago Fireduring the season 12 finale. Eamonn Walker, who played Boden in the NBC procedural drama, had been a series regular since the pilot episode.The actor appeared in all 12 seasons and almost all 252 episodes ofChicago Fire,but his status on the show has come to a close ahead of the season 13 premiere.
Boden has led the firefighters and paramedics of Firehouse 51 as the chief in charge of Battalion 25since the beginning. His guidance and leadership have been a fundamental part ofChicago Fire’s story and other characters' development over the course of the procedural drama’s impressive run on NBC. It’s difficult to put into words how important Boden was for the show, but he will be dearly missed when the 2024–2025 season arrives.
While Eamonn Walker isn’t returning as a series regular forChicago Fireseason 13, some reports claim that the door is open for him to sporadically reprise his role as Boden.
Boden’s excuse for leaving came during the season 12 finale when he tossed his name into the running tobecome the Chicago Fire Department’s Deputy Commissioner.Walker’s character was afraid that the influential job would fall into the wrong hands. So, Boden applied and officially became the Deputy Commissioner when offered the position. While the promotion was quite exciting, it was bittersweet as it meant that Boden had to say goodbye to his family at Firehouse 51. Now,Dermot Mulroney’s Dom Pascal will replace Boden as the chief inChicago Fireseason 13and Walker won’t be a series regular.
One Chicago
Developed by Derek Haas and Michael Brandt, One Chicago is a multi-series television franchise that combines various public service/government organizations in Chicago, Illinois. Each series shares a timeline and universe, with multiple characters crossing over occasionally. The One Chicago universe began with Chicago Fire in 2012, with P.D., Med, and Justice comprising the remainder of one of NBC’s most successful primetime franchises.