Main •
Jesse Spencer as
Lieutenant Matthew "Matt" Casey, Truck Company 81 (seasons 1–10; guest seasons 11–12), a Lieutenant at Firehouse 51 and the officer in charge of Truck Company 81. He serves as second-in-command to Battalion Chief Wallace Boden. Casey is a skilled handyman and carpenter, freelancing as a construction contractor when off-duty. He is civic-minded and becomes an elected
alderman to further serve the city. Despite his reticence and aloof demeanor, he is fiercely protective of the firefighters under him and commands their loyalty and respect. He was briefly engaged to Dr. Hallie Thomas in season one and, from seasons five to seven, was married to Gabriela Dawson. In season 6, he is promoted to Captain by Chief Boden. In the season 9 finale, he begins dating paramedic Sylvie Brett. In season 10, Casey moves to Oregon to take care of Andrew Darden's sons while maintaining a long-distance relationship with Brett. He later returns in the season finale to attend Severide and Kidd's wedding. In the season 11 premiere, Brett breaks up with him, feeling that they had grown apart due to the distance. In the season 11 finale, he returns to Chicago and proposes to Sylvie. They married in season 12. •
Taylor Kinney as Lieutenant Kelly Severide, Rescue Squad 3, a Lieutenant at Firehouse 51, and the officer in charge of Squad 3. In contrast to Casey, he is charismatic and portrayed as something of a "ladies' man". He and Casey have been friends since their days at the CFD Academy. His father was Battalion Chief Benny Severide, a longtime friend of Boden and Henry Mills, father of Candidate Peter Mills. In the season 4 finale, he begins dating Stella Kidd. In season 9, they become engaged. In season 10, they get married. In season 14, he attempts to succeed Dom Pascal as Firehouse 51's Battalion Chief. •
Monica Raymund as Paramedic in Charge Gabriela "Gabby" Dawson, Ambulance 61 (seasons 1–6; guest seasons 7–8), the younger sister of
Detective Antonio Dawson. Dawson is one of the few women at 51 and is usually treated as a sister by the men. She is the Paramedic in Charge of Ambulance 61, but also attends fire academy training to become a firefighter and joins Truck 81. She later transfers back to Ambulance 61 to provide cover for Jimmy Borelli and becomes a foster parent. In season 1, she briefly dates Peter Mills. From seasons 5 to 7, she was married to Casey. In the season 6 finale, she left Chicago to head a rescue-and-relief unit in Puerto Rico, but briefly returned to say goodbye to Casey in the season 7 premiere and again for a charity ball in season 8. •
Lauren German as Paramedic Leslie Elizabeth Shay, Ambulance 61 (seasons 1–2; guest season 3), an experienced paramedic. Shay was the designated ambulance driver and was well-liked by the mostly male crew of 51. She and Kelly Severide shared an apartment as roommates and were best friends. An open
lesbian, she often cracked self-deprecating jokes about it. In the season 3 premiere's continuation of the season 2 finale, she was killed when a serial arsonist intentionally set a trap for first responders. She is then memorialized by her co-workers with an inscription painted on the cab door of Ambulance 61. •
Charlie Barnett as Firefighter Candidate Peter Mills, Truck 81, Squad 3, Ambulance 61 (seasons 1–3), a candidate on Truck 81, following in his deceased father's footsteps. After proving his capabilities as a firefighter, he earns a spot on Squad 3. After losing his firefighter certification due to injury, he transfers to Ambulance 61 to keep working. He eventually recovers and earns his spot back on the squad, but chooses to leave Chicago to work with his family in North Carolina. He briefly dates Gabriela Dawson in season 1. •
David Eigenberg as Senior Firefighter Christopher Herrmann, previously Truck 81, Engine 51, one of the senior firefighters at 51, he serves on Truck 81 before he passes the lieutenant exam, after five previous attempts, and is officially promoted to Lieutenant in season 7, and takes over as officer in charge of Engine Company 51. As a Lieutenant, he serves as fourth-in-command to Battalion Chief Wallace Boden. A father figure to the firehouse, the men and women often come to him for advice. He, Otis, and Dawson jointly invest in a small bar, which they call Molly's. Molly's is also featured on
Chicago P.D. and
Chicago Med as a favorite hangout of cops and medical personnel. In season 13, Boden persuades Herrmann to take the Captain's exam, and despite his doubts, Herrmann passes the exam and is promoted to Captain. In the season 13 finale, Herrmann voluntarily turns in his Captain's bugles and is demoted to firefighter. •
Eamonn Walker as Battalion Chief , Battalion 25 (seasons 1–12; guest season 13), he oversees the firefighters and paramedics of Truck 81, Engine 51, Squad 3 and Ambulance 61 at Firehouse 51. A longtime veteran of the CFD, he is extremely protective of the men and women who serve under him, putting his career on the line several times to help them. He is married to Donna, a teacher, and they have a son named Terrance, who was born in season 3. In season 10, he was promoted to Deputy District Chief. In the season 12 finale, he was appointed as the new Deputy Commissioner of the CFD. In season 13, he returns to investigate a dangerous fire that caused a firefighter to be left trapped inside a burning building. •
Yuri Sardarov as Firefighter , Truck 81 (recurring season 1; seasons 2–8), the latest candidate assigned to 81 before Mills' assignment. He is routinely assigned to work on elevators, and his nickname came from the
Otis Elevator Company. Otis became the driver after Joe Cruz transferred to Squad 3. In the season 8 premiere's continuation of the season 7 finale, he was fatally wounded and died with Cruz by his side in the hospital. •
Christian Stolte as Senior Firefighter Randall "Mouch" McHolland, Truck 81 (recurring season 1; season 2–14), another of 51's senior firefighters, Mouch is the de facto "legal advisor" of 51 and is their union representative. His nickname is a portmanteau of "man" and "couch" since he is almost always seen sitting on the couch in the lounge watching television when not on a call. In season 4, he marries
Sergeant Trudy Platt. In season 13, he is promoted to Lieutenant, although he remains Senior Firefighter aboard Truck 81 with Lieutenant Kidd as the senior officer. He later moves to another firehouse once his engine is decommissioned. •
Joe Minoso as Firefighter Josef "Joe" Cruz, Squad 3 (recurring season 1; main season 2–present), a native of the gangster-infested neighborhood of
Humboldt Park, he spends the first two seasons constantly trying to bail his younger brother out of trouble. In season 3, he briefly dates Sylvie Brett. In the season 3 finale, he transfers to Squad 3. In season 8, he marries Chloe Allen. He was formerly the designated driver for Truck 81 before his transfer to Squad 3. In season 10, his son is born, and they name him Brian Leon "Otis" Cruz. •
Teri Reeves as Dr. Hallie Thomas (season 1), Casey's ex-fiancée. They broke up due to differing views, her hectic schedule, and his irregular hours, which prevented them from spending much time together, but they remained friends. They briefly rekindled their relationship until she was murdered in a fire as part of a cover-up after she discovered one of her colleagues was selling medication to drug dealers. •
Kara Killmer as Paramedic Sylvie Brett, Ambulance 61 (seasons 3–12), a paramedic who joins Ambulance 61 in season three, replacing Leslie Shay after her death. She is from
Fowlerton, Indiana, and is a "runaway bride" who goes up
I-65 to Chicago. Initially, she has difficulty adjusting to city life due to her naivety, as shown by how she leaves cash out on the table with the windows open and rents an apartment in a neighborhood known for crime because the rent was cheap. She briefly dates Joe Cruz in season 3 and shares an apartment with Dawson before the latter's marriage to Casey. After her third partner, Jessica Chilton, is fired for drinking on the job, Sylvie is promoted to Paramedic in Charge in season 4. She dates Dawson's brother, Antonio, on and off from seasons 5 to 6 and is also briefly engaged to Chaplain Kyle Sheffield from seasons 7 to 8. In the season 9 finale, she begins dating Casey, and in season 10, she begins a long-distance relationship with Casey when he moves to Oregon, which she later ends in the season 11 premiere after feeling they have grown apart by distance. In the season 11 finale, Casey returns to Chicago and proposes to Sylvie. They married in season 12. •
Dora Madison as Paramedic in Charge Jessica "Chili" Chilton (recurring season 3; main season 4), brought in to replace Peter Mills as the new Paramedic in Charge. Her arrival is initially met with some frostiness from the rest of the crew since they were still getting over Mills' sudden departure. She was previously with a firehouse in the
West Side and is experienced in dealing with victims of major trauma. She briefly dates Jimmy Borelli in season 4. She is later fired by Chief Boden after the death of her sister causes her to nearly kill a patient by giving them the wrong medicine, and relapse into alcoholism. After she is fired, she calls Severide for help, and he takes her to an Alcoholics Anonymous meeting. •
Steven R. McQueen as Firefighter Candidate James "Jimmy" Borrelli (seasons 4–5), introduced in the season 4 premiere as a new candidate assigned to Truck 81. He briefly dates Jessica "Chili" Chilton in season 4 and also briefly replaces her as a paramedic on Ambulance 61 after Chilton is fired. Early in season 5, after his brother dies in a collapsed building, he blames Chief Boden and transfers back to Truck 81. Shortly thereafter, he is critically injured by an explosion that results in the loss of his left eye, thus ending his firefighting career. •
Miranda Rae Mayo as Firefighter Stella Kidd, Truck 81 (recurring season 4; main season 5–present), introduced in season 4 as Jimmy Borelli's replacement on Truck 81. She briefly replaces Otis as driver in season 6 and permanently replaces him after his death in season 8. In season 9, after passing the exams, she is promoted to Lieutenant. In the season 4 finale, she begins dating Lieutenant Kelly Severide. In season 9, they become engaged. In the season 10 finale, they get married. •
Annie Ilonzeh as Paramedic Emily Foster, Ambulance 61 (seasons 7–8), a former medical student who replaces Gabriela Dawson on Ambulance 61. In the season 8 finale, she reapplies to medical school, and in the season 9 premiere, Brett says she was accepted back and is working in a COVID-19 ward. •
Alberto Rosende as Firefighter Candidate Blake Gallo, Truck 81 (seasons 8–12), Firehouse 51's latest recruit on Truck 81, replacing Brian "Otis" Zvonecek after his death. Gallo became a firefighter after he lost his entire family and house in a fire. He leaves in the season 12 premiere, in which it is revealed he has opted to move to Michigan to be near his relatives. •
Daniel Kyri as Firefighter Candidate Darren Ritter, Engine 51 (recurring seasons 7–8; main seasons 9–13, guest season 14), Herrmann forcibly transfers Firefighter Barnes for his disrespect and Mouch suggests Ritter as a replacement. Previously with Engine 37, Mouch helped Ritter when Ritter froze up during a fire, and Ritter ended up making his first save. He is openly gay. In season 14, he leaves after his boyfriend, Officer Dwayne Monroe, is shot while on duty in
New York City. •
Adriyan Rae as Paramedic Gianna Mackey, Ambulance 61 (season 9), Emily Foster's replacement on Ambulance 61. Gianna grew up in the same neighborhood as Cruz, who recommended her for the job after Foster left and is very protective of her. She quickly makes a good impression on her co-workers and enters a casual relationship with Blake Gallo. She transfers out of Firehouse 51 after being offered a spot at a new firehouse with better advancement opportunities. •
Hanako Greensmith as Paramedic Violet Mikami (recurring seasons 8–9; main season 10–present), a paramedic from Firehouse 20 and Blake Gallo's old rival from the fire academy. She and Gallo briefly dated in season 8. In season 9, Chief Boden asks her to temporarily transfer to Firehouse 51 to fill the spot on Ambulance 61 after Gianna Mackey leaves, and Brett soon convinces her to transfer to Firehouse 51 permanently. Following Sylvie Brett's departure in season 12, Violet was promoted to Paramedic in Charge. • Jake Lockett as Firefighter Samuel "Sam" Carver (recurring seasons 11–12; main season 13; guest season 14), a former rival of Kidd's from the academy recruited to Truck 81. Proving himself a solid firefighter, Carver takes time to warm up to the crew. He works through issues of his own uncaring family and eventually accepts the genuine camaraderie of Firehouse 51. An off-duty carouser and sometimes womanizer, he eases into a romance with Violet by the end of season 12. When the relationship stalls, Carver backslides into destructive behavior, resulting in his attending 12-step meetings for alcoholism and rehab. In the season 13 finale, he revealed he was transferring to the Denver Fire Department to support his sobriety and make a fresh start. •
Jocelyn Hudon as Paramedic Lyla "Lizzie" Novak, (recurring season 12; main season 13–present), Brett's replacement on Ambulance 61, a free-spirited paramedic who preferred to float from firehouse to firehouse until she embraced the stability of 51. Novak is flirtatious with a mischievous sense of humor, but shows herself to be an advocate for the victims she encounters daily on the job. •
Dermot Mulroney as Battalion Chief Dominic "Dom" Pascal, Battalion 25 (seasons 13–14), Boden's replacement as Battalion Chief of Firehouse 51. He is a stoic, dark-humored leader who has returned to Chicago to reunite with his estranged wife after dealing with corruption at his former post in Miami. Pascal's scrutinizing style differs from Boden's, but he quickly establishes respect and allegiance among the crew at 51. He is widowed by a car accident, and he works through his grief by staying on duty. He was let go by the CFD brass after he had been arrested by the FBI for obstructing a federal investigation, and after the charges were dropped, he left Severide as Firehouse 51's commanding officer. •
Brandon Larracuente as Firefighter Salvador "Sal" Vasquez (season 14), a cocky new firefighter and driver for Truck 81. He used to be in the police academy and has a reputation for disobeying his superiors' orders if he sees fit.
Recurring • Randy Flagler as Senior Firefighter Harold Capp, a member of Squad 3. • Anthony Ferraris as Firefighter Tony Ferraris, a member of Squad 3. Outside the show, Ferraris also serves as an active firefighter in real life for the Chicago Fire Department. He has assisted in the production of the series by contributing his expertise from his numerous years of firefighting to bring the show a sense of realism. •
DuShon Monique Brown as Connie (seasons 1–6), Chief Wallace Boden's secretary. •
Mo Gallini as Firefighter Jose Vargas (season 1), a recent transfer to Squad 3 from Truck 81, who's been on the job for 16 years. After an injury sustained in a warehouse fire forces him to retire, he considers suicide by jumping from his apartment building's rooftop. Severide and Casey talk him out of it. •
Shiri Appleby as Clarice Carthage (season 1), the pregnant ex-girlfriend of Leslie Shay. They briefly rekindle their relationship. •
Kathleen Quinlan as Nancy Annalyn Casey (season 1), Matthew and Christie Casey's mother, who was incarcerated for murdering their verbally abusive father and her husband Gregory in 1997, 15 years before the series premiere. She has grown estranged from her children while in prison, but Casey is successful in getting Nancy released, and she stays with him as part of her parole. However, things become tense when Casey voices his discomfort about her going out with a pen pal just hours after being released. She then moves in with her former cellmate, but not before telling her children to mend their relationship. •
Sarah Shahi as Renee Royce (seasons 1–2, 6), a woman who becomes attracted to Kelly and briefly dates him after he saves her in a traffic accident. •
Treat Williams as Benjamin "Benny" Severide (seasons 1–2, 6; guest seasons 4–5, 7), Kelly's father and retired Battalion Chief of Battalion 22, who served with Chief Boden and Henry Mills. He had a love-hate relationship with his son as he previously left Kelly and his mother when he was young. In season 7, he suffers a stroke and dies. • Alexandra Metz as Elise Mills (seasons 1–3), Peter Mills' sister. She helps run the family restaurant with her mom and is torn between being protective of Peter and encouraging him to follow his passion for public service. • Robyn Coffin as Cindy Herrmann, Christopher Herrmann's wife and mother of their five children. • William Smillie as Firefighter Kevin Hadley (seasons 1–3), a member of Squad 3 who is transferred after playing an inappropriate prank on Peter Mills. He later becomes an arsonist and targets his old firehouse, particularly Mills and Severide, whom he blames for his transfer and inability to find a permanent house since. Hadley is eventually stopped and severely burned by his own materials, arrested, and sent to prison for his crimes. He later resurfaces to give Severide information on the arsonist responsible for the deaths of Henry Mills and paramedic Leslie Shay. •
Christine Evangelista as Paramedic in Charge Allison Rafferty, Ambulance 61 (season 2), Dawson's replacement on 61 after she starts training at the academy to become a firefighter. •
Brittany Curran as Katie Nolan (season 2; guest season 7), Benny Severide's daughter and Kelly's half-sister. She works as a chef. •
Michelle Forbes as Gail McLeod (season 2), a financial consultant hired by the state to help trim the budget of the CFD, which includes closing firehouses. •
John Hoogenakker as Lieutenant Spellman (season 2), a firefighter assigned to Firehouse 51, along with Clarke, after city budget cuts force the downsizing of the department. He is eventually outed as Gail McLeod's mole and forced to transfer out of the firehouse. •
Melissa Ponzio as Donna Boden (seasons 2–9, 12), a schoolteacher whom Chief Boden falls for and eventually marries. She is the mother of Terrance, their son. •
Jeff Hephner as Lieutenant Jeff Clarke (seasons 2, 5), a former Marine turned firefighter. After his firehouse is closed, he is transferred to Squad 3. He is initially not well-liked by the rest of the crew since he is extremely private and prefers to read newspapers at the squad's table rather than socialize with them in the lounge. Additionally, his arrival at Firehouse 51 coincides with McLeod's efforts to close it, and he is accused of being her mole. After getting injured on the job, he quits the CFD and starts as a medical student at Chicago Med. •
Edwin Hodge as Firefighter Rick Newhouse, Squad 3 (seasons 2–3), a transfer from the fictional Squad 6. His experience and charismatic personality quickly won over Severide and the rest of the men, although Herrmann initially antagonized him as he had yet to come to terms with the recent suicide of Candidate Rebecca Jones. When off duty, he moonlights as a
skiptracer and entertains his co-workers with stories of his "clientele". •
Warren Christie as Firefighter Scott Rice, Squad 3 (season 3), an old friend of Severide's whom he brings on to replace Newhouse following his transfer. He soon forms a rift between both Squad and Truck after Otis accuses him of ducking fires. After this is confirmed, he admits to being afraid of orphaning his son and is let go from 51. •
Gordon Clapp as Chaplain William Orlovsky (seasons 3–6), a CFD Chaplain who offers spiritual advice and therapy •
Brian J. White as Captain Dallas Patterson, Squad 3 (season 4), a new captain brought in to replace Severide after a review board found the turnover rate for Squad 3 to be too high under his leadership. He later transfers out after ousting corrupt Deputy Chief Riddle, who had been hoping to use him to oust Boden as Battalion Chief. •
Michael Cognata as Julian Robbins (season 6–present), Chief Boden's brother-in-law. •
Damon Dayoub as Firefighter Jake Cordova (season 6), a confident, rugged firefighter who is assigned to Truck 81 as a temporary replacement for Otis after he is injured on a call. •
Tim Hopper as Captain Tom Van Meter (seasons 6–13), a Captain in the Fire Investigations department of the CFD. •
Teddy Sears as Chaplain Kyle Sheffield (seasons 7–8), Orlovsky's replacement as CFD Chaplain. He is briefly engaged to Sylvie Brett from seasons 7 to 8. • Katelynn Shennett as Kylie Estevez (seasons 8–13), the first recruit in the Girls on Fire program, who becomes an office assistant to Chief Boden, then a firefighter at another house until Hermann recruits her to ride Engine at Firehouse 51. •
Jon-Michael Ecker as Lieutenant Greg Grainger (season 9), a Lieutenant from Firehouse 40 temporarily assigned to Engine 51 after Herrmann left on vacation. He briefly casually dates Brett until he realizes she can't commit due to her connection to Casey. • Chris Mansa as Firefighter Mason Locke, Truck 81 (seasons 9–10), an ex-convict who has firefighter training from his time in prison, but has been rejected from the CFD due to his criminal record. Herrmann helps him get a job with the
Saint Paul Fire Department in Minnesota. After Locke returns to Chicago with his record expunged, he is recruited to Truck 81 by Kidd at Herrmann's urging. As of the season 11 premiere, he has transferred to a more rural area and is back to fighting wildfires. •
Brett Dalton as Interim Lieutenant Jason Pelham, Truck 81 (season 10), a floater Lieutenant brought in to temporarily lead Truck 81 following Casey's departure. He starts rough with the team, especially Gallo, but they gradually earn each other's respect. Pelham had been stuck in rotation ever since he forced his former Captain into retirement. Boden learns the full story and trusts Pelham, but many higher-ups in the department hold a grudge against him and try to force him out. Firehouse 51 rallies around Pelham, saving his career. He takes an opportunity to transfer and lead a new team, making way for Kidd to take over. • Jimmy Nicholas as Paramedic Chief Evan Hawkins (seasons 10–11), Chief of Paramedics in the CFD. He has a love affair with Violet, which endures several setbacks until he is tragically killed while protecting a fire victim in season 11. •
Caitlin Carver as Paramedic Emma Jacobs, Ambulance 61 (seasons 10–11), a temporary paramedic filling for Brett, who attempts to sabotage Violet to secure herself a permanent spot at Firehouse 51. She is terminated after fleeing an intense call, but resurfaces in season 11 as an Internal Affairs investigator. Jacobs uses the new position to intimidate 51 until her previous acts of blackmail are proven, and she is fired from the CFD for good. • Pouch the dog (seasons 1–4), a dog given to Mills by a child from a family who could not take care of her. Herrmann, Chief Boden, and Mouch initially decide against it, but eventually agree to let the team adopt her. Pouch's name was suggested by Herrmann as a portmanteau of "pooch" and "couch". In season 4, 51 allows her to be adopted by the son of a CPD detective killed in the line of duty to help him with his grief. • Tuesday the dog (seasons 7–10), a Dalmatian dog belonging to Ritter. She has separation anxiety, so Ritter brings her to the firehouse and she ends up becoming the firehouse dog, replacing Pouch. •
Rome Flynn as Derek Gibson (season 12), a firefighter and former amateur boxer with a dark past. He leaves to seek treatment for a drug addiction. • Michael Bradway as Jack Damon (seasons 12–13), a firefighter who joins Truck 81 and is later revealed to be Kelly Severide's paternal half-brother. •
KaDee Strickland as Monica Pascal (season 13), the estranged wife of Battalion Chief Dominic “Dom” Pascal. She is eventually killed in a car accident. ==Episodes==