List of 9-1-1 characters

9-1-1 is an American television series that originally began broadcasting on January 3, 2018, on Fox.

Overview

Character	Portrayed by	Seasons
		1	2	3	4	5	6	7	8
Main Cast
Athena Grant-Nash	Angela Bassett	Main
Robert "Bobby" Wade Nash	Peter Krause	Main
Evan "Buck" Buckley	Oliver Stark	Main
Henrietta "Hen" Wilson	Aisha Hinds	Main
Howard "Chimney" Han	Kenneth Choi	Main
Michael W. Grant	Rockmond Dunbar	Main					Does not appear
Abigail "Abby" Clark	Connie Britton	Main	Does not appear	Special Guest	Does not appear
Maddie Buckley-Han	Jennifer Love Hewitt	Does not appear	Main
Edmundo "Eddie" Diaz	Ryan Guzman	Does not appear	Main
May Grant	Corinne Massiah	Recurring	Main					Guest	TBA
Harry Grant	Marcanthonee Jon Reis	Recurring	Main				Credit only	Does not appear
	Elijah M. Cooper	Does not appear						Recurring	TBA
Christopher Diaz	Gavin McHugh	Does not appear	Recurring	Main
Albert Han	John Harlan Kim	Does not appear		Guest	Main	Recurring	Guest	Does not appear	TBA
Recurring Cast
Karen Wilson	Tracie Thoms	Recurring
Officer Carol Branford	Michelle Bernard	Recurring
Carla Price	Cocoa Brown	Recurring		Guest	Recurring	Guest		Does not appear
Terry Flores	Alex Loynaz	Recurring		Guest	Does not appear	Guest	Does not appear
Eva Mathis	Abby Brammell	Recurring	Guest	Does not appear		Guest	Does not appear
Father Brian	Gavin Stenhouse	Recurring	Guest	Does not appear					Guest
Patricia Clark	Mariette Hartley	Recurring	Does not appear
Denny Wilson	Declan Pratt	Guest	Recurring
Susan "Sue" Blevins	Debra Christofferson	Guest	Recurring				Guest
Elaine Maynard	Claudia Christian	Guest		Recurring	Guest	Recurring	Guest		Recurring
Josh Russo	Bryan Safi	Does not appear	Recurring
Linda Bates	Chiquita Fuller	Does not appear	Recurring				Guest	Does not appear
Isabel Diaz	Ana Mercedes	Does not appear	Recurring	Guest			Does not appear	Guest	Does not appear
John	Jonathan Grebe	Does not appear	Recurring	Guest	Does not appear
Shannon Diaz	Devin Kelley	Does not appear	Recurring	Guest	Does not appear			Guest	Does not appear
Kim		Does not appear						Guest	Does not appear
Dwight	Rick Chambers	Does not appear	Recurring	Does not appear	Guest	Does not appear
Ali Martin	Tiffany Dupont	Does not appear	Recurring	Does not appear
Thomas "Tommy" Kinard	Lou Ferrigno Jr.	Does not appear	Recurring	Does not appear				Recurring
Douglas "Doug" Kendall	Brian Hallisay	Does not appear	Recurring	Does not appear			Guest		Does not appear
Beatrice Carter	Beverly Todd	Does not appear	Guest		Does not appear		Recurring	Does not appear
Taylor Kelly	Megan West	Does not appear	Guest	Does not appear	Recurring		Guest	Does not appear
Samuel Carter	Henry G. Sanders	Does not appear	Guest	Does not appear			Recurring	Does not appear
Nathaniel Greene	Troy Winbush	Does not appear	Recurring	Does not appear			Recurring	Does not appear
Officer Williams	Chris Wu	Does not appear		Recurring			Guest		Does not appear
Jamal Momed	Ashwin Gore	Does not appear		Recurring			Does not appear
Lena Bosko	Ronda Rousey	Does not appear		Recurring	Does not appear
Tara	Ellen Hollman	Does not appear		Recurring	Does not appear
Vincent	Scott Speiser	Does not appear		Recurring	Does not appear
Greg	Sean Kleier	Does not appear		Recurring	Does not appear
Ronald "Ronnie" Cooper	Leonard Roberts	Does not appear		Recurring	Does not appear
Dr. Calloway	Christian Keyes	Does not appear		Recurring	Does not appear
Dr. David Hale	La Monde Byrd	Does not appear		Guest	Recurring		Does not appear
Ana Flores	Gabrielle Walsh	Does not appear		Guest	Recurring		Does not appear
Det. Louis Ransone	Sasha Roiz	Does not appear		Guest		Recurring	Does not appear
Jeffrey Connor Hudson	Noah Bean	Does not appear		Guest	Does not appear	Recurring	Does not appear
Antonia "Toni" Wilson	Marsha Warfield	Does not appear			Recurring	Guest		Does not appear
Diedra	Andi Chapman	Does not appear			Recurring	Does not appear	Guest		Does not appear
Nia Wilson	Margot Terry	Does not appear			Recurring	Does not appear
Ravi Panikkar	Anirudh Pisharody	Does not appear			Recurring				Does not appear
Lila Risco	Carly Nykanen	Does not appear				Recurring	Does not appear
Claudette Collins	Vanessa Estelle Williams	Does not appear				Recurring	Does not appear
Jonah Greenway	Bryce Durfee	Does not appear				Recurring	Does not appear
Lucy Donato	Arielle Kebbel	Does not appear				Recurring		Does not appear
Noah Carmack	Alfonso Caballero	Does not appear					Recurring	Does not appear
Marisol	Edy Ganem	Does not appear					Recurring		Does not appear
Mara Driskell	Askyler Bell	Does not appear						Recurring
Julian Enes	Rick Cosnett	Does not appear						Recurring	Does not appear
Captain Vincent Gerrard	Brian Thompson	Does not appear	Guest	Does not appear	Guest	Does not appear		Recurring

Main characters

Athena Grant-Nash

Athena Grant-Nash
9-1-1 character
First appearance	"Pilot" (1.01)
Created by	Ryan Murphy Tim Minear Brad Falchuk
Portrayed by	Angela Bassett Ayaamii Sledge (child) Pepi Sonuga (young adult)
In-universe information
Full name	Athena Grant-Nash Athena Carter (birth name)
Occupation	Field Sergeant (Los Angeles Police Department)
Family	Beatrice Carter (mother) Samuel Carter (father)
Spouse	Bobby Nash ​ (m. 2019)​ Michael Grant ​ (div. 2018)​
Significant others	Emmett Washington † (late fiancé)
Children	May Grant (daughter) Harry Grant (son)
Origin	Belleville, Florida, USA

Angela Bassett portrays Athena Grant-Nash.

Athena Grant-Nash (née Carter) (Angela Bassett) is an LAPD patrol sergeant, and mother of May and Harry from her first marriage to Michael Grant. Athena left her home in Florida for Los Angeles to become a police officer as a result of the failed investigation into the murder of her friend and neighbor Tanya Kingston (a murder she helps to solve 45 years later). She is extremely independent, preferring a one-person patrol unit to working with a partner (although she does work with detectives on certain cases) and is extremely tenacious when it comes to solving crimes or chasing down suspects (including the killer of her fiancé decades later after the murder weapon is recovered). However, she can be impetuous and has gone into dangerous situations without back-up (on one occasion getting ambushed and almost killed by a dangerous suspect). Athena and Michael divorce in the first season, and at the end of Season One, she begins dating Bobby Nash, marrying him at the end of the second season. Because of Buck's own impetuosity in dangerous or stressful situations, she is both exasperated by and understanding of him. Due to the traumas, she has suffered in the past, she rarely shows her emotional side (except to Hen) but has begun allowing Bobby in (although at the beginning of Season 7, she has begun to worry that apart from the constant excitement and danger in both their jobs she and Bobby may not have enough in common to sustain their marriage). Pepi Sonuga portrays a younger Athena during the flashback scenes of an episode of season 3 in which she learns that the weapon used to murder her fiancé has been found.

Bobby Nash

Peter Krause portrays Bobby Nash.

Bobby Nash
9-1-1 character
First appearance	"Pilot" (1.01)
Created by	Ryan Murphy Tim Minear Brad Falchuk
Portrayed by	Peter Krause Mark Sodukh (child)
In-universe information
Full name	Robert Wade Nash
Nickname	Bobby
Occupation	Station 118 Captain (Los Angeles Fire Department)
Family	Ann Nash (mother) Tim Nash † (father) Charlie Nash (brother)
Spouse	Athena Grant ​ (m. 2019)​ Marcy Nash ​ (died 2014)​
Children	Robert Nash Jr. † (son) Brook Nash † (daughter) May Grant (step-daughter) Harry Grant (step-son)
Origin	St. Paul, Minnesota, USA

Robert "Bobby" Wade Nash (Peter Krause) is the Captain of Station 118 of the Los Angeles Fire Department and later Athena's husband. A recovering alcoholic, before arriving in Los Angeles Bobby lived in Minnesota where his wife and two children died in a fire caused by a faulty propane heater (which he had been using while he was drunk in an empty apartment of the building they were living in, which additionally was not up to code) and blamed himself for not only their deaths but also 145 other people in the building. Originally planning to commit suicide after saving 145 lives as atonement, his friendship/camaraderie with the members of the 118 and his blossoming relationship with Athena helps him put his demons to rest, and he becomes a beloved stepfather to May and Harry and a father figure to Buck. He is also the 118's resident "chef" (although Athena runs him a close second). After a rocky year, he transferred to the LAFD (with his superiors in Minnesota "sanitizing" his record to allow the transfer) and took command of the 118 (which had had six previous captains in the span of two years, giving the station a somewhat unsavory reputation). Now in the present, he has helped to make the 118 a stationhouse to aspire to within the LAFD and create a team which he himself has described as "magic". He is very good friends with Athena's ex-husband Michael, and Athena's daughter May has acknowledged him as her other father. At the end of Season 7, he temporarily resigns from his post as Captain but is convinced to return, only to find that his position has been filled by Captain Gerrard. He then takes up a temporary job as a technical advisor on the meta-firefighter show Hotshots before regaining his captain position by convincing Gerrard to take his place as Hotshots' advisor.

Evan Buckley

Evan Buckley
9-1-1 character
First appearance	"Pilot" (1.01)
Created by	Ryan Murphy Tim Minear Brad Falchuk
Portrayed by	Oliver Stark Beckett Maillard (child) Elton McCrudden (teenager)
In-universe information
Full name	Evan Buckley
Nickname	Buck
Occupation	Station 118 Firefighter (Los Angeles Fire Department)
Family	Margaret Buckley (mother) Phillip Buckley (father) Maddie Buckley (sister) Daniel Buckley † (brother) Jee-Yun Buckley-Han (niece)
Significant other	Tommy Kinard (ex-boyfriend) Abigail Clark (ex-girlfriend) Ali Martin (ex-girlfriend) Taylor Kelly (ex-girlfriend) Natalia Dollenmeyer (ex-girlfriend)
Origin	Hershey, Pennsylvania, USA

Evan "Buck" Buckley (Oliver Stark) is firefighter at Station 118 and Maddie's younger brother. Joined the LAFD after a series of jobs in various parts of the country. While he can be impetuous to the point of recklessness while in the field, he is dedicated to his job. Because of his dysfunctional relationship with his own parents, he sees and trusts Bobby as a father figure and the members of the 118 as his family. He convinced his sister Maddie to join the 9-1-1 Emergency Dispatch, introduced Abby's mother's former caretaker Carla to Eddie Diaz, and has become a somewhat "co-parent" to Eddie's son Christopher. Buck was an uncontrollable womanizer at first (which nearly cost him his job in Season 1, since he was using LAFD property to facilitate his liaisons), but after meeting Abby he started looking for serious relationships. After Abby's departure, he reverted to "hit-and-run" relationship until he met TV reporter Taylor Kelly, a relationship which lasted in seasons 4-5, until it was shattered by Taylor's betrayal of Buck's trust. In Season 6, he agrees to be a sperm donor for an old friend and his wife who are having fertility problems. In the seventh season, he realizes he is bisexual and begins dating former 118 firefighter Thomas Kinard, they later break up.

Edmundo Diaz

Ryan Guzman portrays Edmundo Diaz

Edmundo Diaz
9-1-1 character
First appearance	"Under Pressure" (2.01)
Created by	Ryan Murphy Tim Minear Brad Falchuk
Portrayed by	Ryan Guzman
In-universe information
Full name	Edmundo Diaz
Nickname	Eddie
Occupation	Station 118 Firefighter (Los Angeles Fire Department) United States Army combat medic (formerly)
Family	Helena Diaz (mother) Ramon Diaz (father) Sophia Diaz (sister) Adriana Diaz (sister)
Spouse	Shannon Diaz ​ ​ (m. 2010; died 2019)​
Significant other	Ana Flores (ex-girlfriend) Marisol (ex-girlfriend) Kim (emotional affair)
Children	Christopher Diaz (son)
Origin	El Paso, Texas, USA

Edmundo "Eddie" Diaz (Ryan Guzman) is a firefighter and Christopher's father. A Texas native, he served in the United States Army as a combat medic and moved to Los Angeles after being discharged, joining the 118 fresh out of the academy. He served in Afghanistan and his combat experience is shown through his ability to think quickly on his feet even under duress with minimal back-up. He becomes best friends with Buck (after some initial jealousy on Buck's part) and the two are usually partnered while on calls. Formerly married to Shannon, he is a single father and has a son named Christopher (who was born when they were both 19). Shortly after Eddie returned from Afghanistan, he and Christopher moved to Los Angeles to escape his parents who viewed him incapable of caring for his son. He named Buck to be the legal guardian of his son Christopher in his will in the event of his death, thus emphasizing the fact that Buck has been a constant presence in his life as well as his son's. With Carla's help, he has done well as a single parent (although at times he has been a little too over-protective of his son) and is gradually coming to terms with his son's growing up (although at the beginning of Season 7, he is somewhat thrown by Christopher's growing relationship with girls to the point of asking Buck to talk to Christopher on the subject).

Henrietta Wilson

Henrietta Wilson
9-1-1 character
First appearance	"Pilot" (1.01)
Created by	Ryan Murphy Tim Minear Brad Falchuk
Portrayed by	Aisha Hinds
In-universe information
Full name	Henrietta Wilson
Nickname	Hen
Occupation	Firefighter & paramedic, Station 118 (Los Angeles Fire Department) Pharmaceutical sales representative (formerly)
Family	Antonia Wilson (mother) Byron Wilson † (father)
Spouse	Karen Wilson
Significant other	Eva Mathis (ex-girlfriend)
Children	Denny Wilson (adoptive son) Mara Driskell (adoptive daughter)

Henrietta "Hen" Wilson (Aisha Hinds) is a firefighter & paramedic at Station 118. Originally a pharmaceutical representative, she left that job and joined the LAFD as a paramedic after saving her life coach with CPR. She was accepted at Station 118 and became partners and close friends with Chimney. She was originally in an emotionally abusive relationship with Eva, but after Eva was imprisoned, she met Karen (via a blind date Chimney set up) and later married her; they have an adopted son named Denny (the biological son of Hen's former partner Eva) and an adopted daughter named Mara. In Season 3, Hen decides to apply to medical school and is accepted but is unable to fully balance her hectic school schedule with her paramedic job and her family life, and fails a critical examination. She is allowed to return to medical school, but eventually quits in Season 6, preferring to remain a paramedic. In Bobby's absence, she is Interim Captain (despite the fact that Chimney is senior to her).

Howard Han

Howard Han
9-1-1 character
First appearance	"Pilot" (1.01)
Created by	Ryan Murphy Tim Minear Brad Falchuk
Portrayed by	Kenneth Choi
In-universe information
Full name	Howard Han
Nicknames	Howie Chimney Chim
Occupation	Firefighter & paramedic, Station 118 (Los Angeles Fire Department)
Family	Jee-Yun Han † (mother) Sang Han (father) Han Myung-Soon (stepmother) John Lee (foster father) Anne Lee (foster mother) Albert Han (half-brother) Kevin Lee † (foster brother)
Spouse	Maddie Buckley ​ (m. 2024)​
Significant other	Tatiana (ex-girlfriend)
Children	Jee-Yun Buckley Han (daughter)

Howard "Chimney" Han (Kenneth Choi) is a firefighter & paramedic at Station 118, and Maddie's husband. The reason why he's nicknamed "Chimney" and how he got the nickname is a closely guarded secret and to date has not been revealed. He grew up in the Los Angeles area with his mother while his father returned to South Korea, divorced Chimney's mother and remarried; as a result, he has a very testy relationship with his father, especially after the elder Mr. Han openly expressed his disappointment in Chimney's chosen profession. After his mother's death, Chimney was raised by the Lee family (his mother and Mrs. Lee were best friends) and looks on them as his family. He has a younger half-brother named Albert, who secretly left South Korea to escape their father's control and lived with him for a while. At the end of season three they find out Maddie is pregnant, and they now have a daughter named Jee-Yun. In Season 6, he, Maddie and their daughter move into a house together, and at the end of the season, they get engaged, and are later married in the sixth episode of the seventh season.

Maddie Han

Maddie Han
9-1-1 character
First appearance	"Under Pressure" (2.01)
Created by	Ryan Murphy Tim Minear Brad Falchuk
Portrayed by	Jennifer Love Hewitt Maddie Levy (child) Molly Jackson (young adult)
In-universe information
Full name	Maddie Han Maddie Buckley (birth name) Maddie Kendall (former married name)
Occupation	Emergency dispatcher Nurse (formerly)
Family	Margaret Buckley (mother) Phillip Buckley (father) Evan Buckley (brother) Daniel Buckley † (brother)
Spouse	Howard Han ​ (m. 2024)​ Doug Kendall ​ (died 2019)​
Children	Jee-Yun Buckley Han (daughter)
Origin	Hershey, Pennsylvania, USA

Jennifer Love Hewitt portrays Maddie Han.

Maddie Han (née Buckley) (Jennifer Love Hewitt) is 911 operator, Buck's sister, and Chimney's wife. Originally a nurse at a Boston hospital, Maddie fled to Los Angeles to escape her emotionally and physically abusive husband, Doug Kendall. Buck was instrumental in helping her get a job as a 911 Emergency Dispatcher, and she would later kill Doug in self-defense after he stabbed Chimney and kidnapped her. At the end of season three, she finds out she is pregnant with her and Chimney's child. In the conclusion of Season 4, due to her various emotional traumas after giving birth, Maddie quits her job, and in Season 5 due to postpartum depression she leaves Chimney and their baby because she doesn't think she would be a good mother for the baby and travels back to Boston to enter a program. She and Chimney (who has followed her, along with their daughter) are reunited on St. Patrick's Day, and she returns with them to Los Angeles, where she resumes her job as a 911 Operator. (season 2 – present) After she and Chimney get back together at the beginning of season 6, she proposes to him at the end of the season, and the two are later married in season 7.

Christopher Diaz

Gavin McHugh as Christopher Diaz, Eddie's son. Born with cerebral palsy, which has not affected his intelligence. Develops a relationship with Buck to the point where Eddie officially makes Buck Christopher's legal guardian in case of anything serious happening to Eddie (season 3 – present; recurring season 2). He is extremely sweet-natured and shows remarkable empathy with other troubled people. While he seems to have come to terms with the death of his mother (killed in a traffic accident in Season 2), at the beginning to Season 7, he is worried that he has begun to forget her (which Eddie remedies by giving Christopher a letter she had written to Christopher years ago). At the end of Season 7, he leaves to live with his grandparents in Texas upon learning of Eddie's affair with Kim.

Former main characters

May Grant

Corinne Massiah as May Grant, Athena and Michael's daughter. Graduates high school at the end of season three. Because of the attack on her mother in Season 3, she begins training and becomes a 911 operator in season 4 (despite Athena's initial resistance). Leaves Emergency Dispatch to pursue college education in Season 6. (seasons 2 – 6; recurring season 1; guest season 7)

Harry Grant

Marcanthonee Jon Reis as Harry Grant, Athena and Michael's son (seasons 2 – 6; recurring Season 1). Elijah M. Cooper as Harry Grant, Athena and Michael's son (Season 7).

Albert Han

John Harlan Kim as Albert Han, Chimney's half-brother. Secretly left South Korea to escape his father's authoritarianism and came to Los Angeles. Stayed with Chimney for a while after a rocky reunion, then with Buck after Maddie moved in. Was involved and seriously injured in a major freeway accident but rescued by the 118. Joined the LAFD and became a full firefighter at the end of Season 4, but later quit (Season 4; guest Seasons 3, 5)

Michael Grant

Rockmond Dunbar as Michael W. Grant, Athena's ex-husband. The two amicably divorce after he comes out as gay. He and Athena remain close friends and confidants, and the friendship extends to her new husband Bobby. He leaves Los Angeles with his fiance David to work in Haiti after David decides to go help with that country's medical emergencies after the devastating storms of 2021 (Season 1–5).

Abigail Clark

Connie Britton as Abigail "Abby" Clark, 911 operator. Abby leaves at the end of season one to travel the world following her mother's passing. She never returned to Los Angeles until the Season 3 finale to give Buck closure, becoming engaged and living in Arizona (Season 1; special guest Season 3).

Recurring characters

This is a list of recurring actors and the characters they portrayed in multiple episodes, which were significant roles, sometimes across multiple seasons.

Introduced in season 1

• Mariette Hartley as Patricia Clark, Abby's mother, who suffers from Alzheimer's. She passes away in the penultimate episode of season 1
• Gavin Stenhouse as Priest
• Alex Loynaz as Terry Flores, 911 technician
• Cocoa Brown as Carla Price, Abby's mother's nurse and later a nanny/health-aide for Christopher Diaz
• Claudia Christian as Captain Elaine Maynard, Athena's direct superior at the LAPD
• Tracie Thoms as Karen Wilson, Hen's wife, an aerospace industry engineer
• Abby Brammell as Eva Mathis, Hen's substance-addicted ex-girlfriend and Denny's biological mother
• Declan Pratt as Denny Wilson, Hen and Karen's adopted son
• Debra Christofferson as Sue Blevins, 911 call center manager
• Michelle Bernard as Carol Branford, an LAPD officer under Athena's command

Introduced in season 2

• Chiquita Fuller as Linda Bates, 911 operator
• Bryan Safi as Josh Russo, 911 dispatch's supervisor and training officer and Maddie’s best friend
• Tiffany Dupont as Ali Martin, Buck's girlfriend who left him off-screen before season 3 premiered
• Jonathan Grebe as John, a paramedic
• Ana Mercedes as Isabel Diaz, Eddie's grandmother
• Devin Kelley as Shannon Diaz, Eddie's estranged wife and Christopher's mother who is later killed off in a road accident. In Season 7, Kelley returns to play a woman named Kim who is a dead ringer for Shannon, leading to Eddie having a brief emotional affair with her.
• Freda Foh Shen as Anne Lee, who raised Chimney after his mother died.
• Kelvin Han Yee as John Lee
• James Chen as Kevin Lee - Chimney's "brother", who becomes a firefighter along with Chimney and is killed in the line of duty.
• Rick Chambers as Dwight Meyerson, a news reporter
• Lou Ferrigno Jr. as Thomas "Tommy" Kinard - a firefighter with the 118 prior to 2005 up to some time prior to 2018, when he moved to the aerial division - 217. He returns in season 7, is revealed to be gay, and begins a relationship with Buck. They later break up.
• Brian Thompson as Captain Vincent Gerrard - the captain of the 118 prior to 2005 up to 2008 when he was dismissed for racial prejudice. He returns in season 7, where he takes over the 118 following Bobby's resignation. He is especially harsh on Buck, but softens up when Buck saves him from a malfunctioning saw. Eventually, he leaves the 118 after helping Bobby and Hen take down Councilwoman Ortiz.
• Brian Hallisay as Doug Kendall / Jason Bailey, Maddie's abusive ex-husband (Brian Hallisay is Jennifer Love Hewitt's husband)
• Megan West as Taylor Kelly, a TV reporter who dates Buck in season 2, then resumes their relationship in season 4 and leaves in season 5.
• Danny Nucci as Detective Rick Romero.
• Troy Winbush as Nathaniel Greene, Denny's biological father.

Introduced in season 3

• Chris Wu as Officer Williams, an LAPD officer under Athena's command
• Ronda Rousey as Firefighter Lena Bosko
• Leonard Roberts as Captain Ronnie Cooper
• Theo Breaux as Firefighter Stover
• Joe Pistone as Firefighter Calley
• Peter Jang as Firefighter Logan
• Ashwin Gore as Jamal Momed, 911 Operator
• Sean Kleier as Greg, an armed robber who seduces Josh in order to clone his access card and hold dispatch hostage
• Gabrielle Walsh as Ana Flores, Christopher's teacher in Season 3. She dated Eddie in season 4 and 5, until he broke up with her.
• Sasha Roiz as Detective Lou Ransone, a colleague of Athena, who reappears in season 4 and season 5 and is injured by the serial rapist who attacked Athena.

Introduced in season 4

• Margot Terry as Nia, a young girl Hen and Karen foster
• Anirudh Pisharody as Ravi Panikkar, a probationary firefighter with the 118 who appears sporadically in season 4, became a regular in season 5
• Marsha Warfield as Antonia 'Toni' Wilson, Hen's mother

Introduced in season 5

• Vanessa Estelle Williams as Claudette Collins, an outspoken call center veteran, who transfers back to the LA station, intimidating May Grant.
• Bryce Durfee as Jonah Greenway, a new Firefighter/paramedic filling in for Chimney at Station 118, who is later revealed to be a serial killer.
• Arielle Kebbel as Lucy Donato, a new firefighter filling in for Eddie at Station 118.

Introduced in season 6

• Alfonso Caballero as Noah Carmack, a new intern at the dispatch center who works under Maddie's supervision.
• Edy Ganem as Marisol, Eddie's ex-girlfriend

Guest stars

The following is a supplementary list of guest stars, some recurring, who appear in lesser roles.

Introduced in season one

• John Marshall Jones as Dave Morrisey
• Rachel Breitag as Tatiana, Chimney's ex-girlfriend
• Troy Ian Hall as Police Officer
• Doug Savant as Matthew Clark, Abby's brother
• Wolé Parks as Glenn, Michael's ex-boyfriend; later replaced by Reggie Austin in season 2
• Genneya Walton as Laila Creedy
• Brielle Barbusca as Cooper
• Josephine Lawrence as Georgina
• Noelle E. Parker as Brook Nash, Bobby's late daughter
• London Cheshire as Robert Nash Jr., Bobby's late son
• Laura Allen as Marcy Nash, Bobby's late wife
• Colby French as Detective Andy Marks
• Jennifer Aspen as Lorraine, an insurance fraudster and former porch pirate
• Todd Williams as Aaron Brooks, Athena's ex-boyfriend

Introduced in season two

• Connor Trinneer as Jessie
• Eric Nenninger as Brian
• Ali Hillis as Jen
• T. J. Linnard as Russ
• Romi Dias as Chief Miranda Williams
• Connor Dean as Tucker
• Nev Scharrel as Kat
• Kendra Chell as Ainsley
• Burt Grinstead as Drew Hudson
• Terri Hoyos as Aunt Josephina, Eddie's aunt
• Christine Estabrook as Gloria Wagner, a 911 dispatcher fired for negligence
• Justin James Farley as Bret
• Romy Rosemont as Lola Peterson. Lola returns in the first three episodes of Season 7.
• Daniel Roebuck as Norman Peterson. Norman returns in the first three episodes of Season 7.
• Gino Anthony Pesi as Sal Deluca, a firefighter with the 118 prior to 2008 until he was transferred to the 122 by Bobby for insubordination
• Mark Derwin as Captain Thomas
• Tyler Ross as Brandon Skinner
• Beverly Todd as Beatrice Carter, Athena's mother
• Joseph Lyle Taylor as Marty Collins, the 118's resident mechanic
• Lauren Stamile as Ellie Costas
• Anthony Turpel as Freddie Costas, a serial bomber who tries to kill Athena and Bobby for jailing his late father over an insurance fraud fire
• Michael Whaley as Commander Bowman
• Julian Works as Marvin Chavez, cousin of Mateo Chavez (Austin firefighter, station 126)

Introduced in season three

• William Russ as Chuck
• Ava Acres as Charlotte
• Brian Tichnell as Max Green
• Elia Cantu as Stacy Green
• Deborah Strang as Adele Summers
• Conor Romero as Jason Summers
• Ellen Hollman as Tara, a domestic abuse victim Maddie tries unsuccessfully to help
• Jordan Belfi as Chase Mackey
• Scott Speiser as Vincent
• Jayson Blair as Jake
• Rumer Willis as Georgia

Introduced in season four

• Nikki DeLoach as Janell Hansen
• Vanessa Marano as Sydney
• Gregory Harrison as Phillip Buckley
• Dee Wallace as Margaret Buckley
• Leah Pipes as Molly
• Merrick McCartha as Aldous Pate