NCIS: Los Angeles

• G. Callen (birthname Grisha Aleksandrovich Nikolaev) (Chris O'Donnell) is the Lead Senior Field Agent and undercover operative attached to the NCIS Office of Special Projects. He speaks several languages fluently, including Russian, German, and French. Callen is a highly skilled field agent having worked numerous overseas undercover assignments. Placed in the foster system at a young age, G. did not know his first name but eventually learned about his family, and in turn, himself. As G. has somewhat of a nomadic nature, Los Angeles is G's most stable home. He is partnered with Sam Hanna.[12]
• Nate Getz (Peter Cambor) is an Operational Psychologist originally attached to OSP in order to monitor the team's emotional well-being. Valued as both an agent and a doctor, Getz is later drafted to a deep cover operation and subsequently becomes a well-established field agent. Despite his career change, Getz still returns to Los Angeles when needed. (season 1; recurring seasons 2–8)
• Kensi Blye (Daniela Ruah) is the daughter of a Marine and, initially, the only female Field Agent attached to OSP. Her father died at a young age, after which Kensi spent some time living on the streets. Estranged from her mother, Kensi is a skilled undercover operative and sniper who is not afraid to use her sexuality to get results. In season 10, she marries her partner Marty Deeks and the two later purchase and run a bar called "The Squid and Dagger".
• Dominic Vail (Adam Jamal Craig) is a probationary agent and a technical specialist who was assigned to OSP straight out of training. He is partnered with Kensi and seen as a sort of younger brother to the other team members; NCIS Los Angeles is left devastated when, following a period as a missing person, Dom is killed during his own rescue mission when he saves Sam from an unseen assailant. (season 1)
• Sam Hanna (LL Cool J) is a Senior Field Agent attached to OSP and G's partner. Sam has the most stable home life of the team as he is married with children through most of the series, though his wife is murdered in season 8 just after returning to her own position. He met his wife on the job and still lives for the thrill of undercover work. He is a former Navy SEAL, an expert on Middle Eastern culture, and a fluent Arabic speaker; as such, he provides invaluable insights on cases involving the USMC and USN.[6]
• Henrietta "Hetty" Lange (Linda Hunt) is a Supervisory Special Agent and the team's Operational Manager. As a veteran undercover operative, Hetty has achieved an unbelievable amount during her life, with distinguished work as an overseas intelligence operative during the Cold War. During her younger years, she took in several orphans (including Callen and Hunter) from the streets in order to mold them into undercover operatives.
• Eric Beale (Barrett Foa) is the team's Technical Operator and resident geek. He was not an undercover operative like his teammates until season seven, so was not firearms-trained until then. Beale is incredibly comfortable in the OSP much to the chagrin of his teammates who often become annoyed by his quirks such as leaving his surf board by their cars. He is partnered and in a romantic relationship with Nell. (season 1 onwards; recurring season 1)
• Marty Deeks (Eric Christian Olsen) is an NCIS Special Agent and a former veteran Los Angeles Police Department Detective who worked undercover and was exiled socially within the LAPD. Deeks is also an experienced attorney at law having worked as a Public Defender in the Los Angeles Criminal Courts prior to joining the LAPD. After he is selected by Hetty to be the LAPD's Liaison Detective to NCIS, it becomes clear that her plan is for Deeks to ultimately become an Agent. He did not have the easiest childhood and deflects a great deal using humor. He is partnered with Kensi and later develops a romantic relationship with her, which leads to their eventual marriage in season 10; the two also buy a bar the same season, naming it "The Squid and Dagger". In season 12, Deeks loses his liasion position as a result of ongoing reform in the LAPD, and is furloughed by the department until budget issues involving the reform are resolved. After initially being told that he's too old to become an Agent at this point, Deeks is eventually accepted for FLETC training thanks to Hetty pulling some strings. Although he seemingly supposedly washes out of training just before graduation, it's revealed that Hetty had arranged for him to get his badge by her, officially making him an NCIS Special Agent. (season 2 onwards; recurring season 1)[13]
• Nell Jones (Renée Felice Smith) is a Special Agent who acts as the team's intelligence analyst. She is just as comfortable outside the office as in it, and it appears that Hetty is grooming her as a replacement. Jones is a highly capable field operative and extremely skilled firearms expert. She has the highest IQ of anybody at NCIS. She is partnered and involved in a romantic relationship with Eric. (season 2 onwards; recurring season 2).
• Owen Granger (Miguel Ferrer) is the Assistant Director of NCIS. He is the team's link to Washington, and while he is often seen at loggerheads with his subordinates, he no doubt has a great desire to keep them safe. Unlike other administrators, he is not afraid to accompany the team into the field. Granger spent many years overseas as a field agent on many hazardous assignments before becoming an administrator. He is a long time friend and sometimes adversary of Hetty. During season 8, Granger is revealed to be suffering from an unknown ailment, most likely cancer, due to a lifetime of bad habits. In the episode "Payback" (Miguel Ferrer's final episode filmed before his death), after being wounded by rogue CIA operatives, Granger disappears from the hospital. In the following season, Granger's daughter, Jennifer Kim (Malese Jow), confirms his death from his illness. (seasons 5–8; recurring seasons 3–4)
• Shay Mosley (Nia Long) is a former Secret Service agent who becomes the NCIS Executive Assistant Director for Pacific Operations (EAD-PAC). She comes off as hardened and cold towards the team, but eventually, they warm up to each other, especially following Hetty's return. She is revealed to have a son named Derrick, who was taken by his father, criminal arms dealer Spencer Williams, when Williams fled the country for Mexico five years prior. At the end of season 9, she enacts an unsanctioned mission for the team to head into Mexico and retrieve Derrick. While the mission is ultimately successful (during which Mosley kills Williams), it comes at a costly price: Mosley's assistant Agent Harley Hidoko is killed, the rest of the team is grievously wounded, and the OSP is put under the microscope by D.C. officials. In season 10, after a drug cartel allied with Williams puts bounties on the team's heads, Mosley opts to take full responsibility for everything, resigns her post, and flees with her son into hiding. (seasons 9–10)
• Fatima Namazi (Medalion Rahimi) is an NCIS Special Agent. She first appears halfway through in season 10, where she helps the team pursue a terrorist cell responsible for bombing a movie theater in the first of a series of planned attacks on Los Angeles. From then on, Namazi appears periodically, helping the OSP team with cases from either in the Ops Center or out in the field, until she is reassigned overseas to Afghanistan early the following season. In the second half of season 11, she is captured by insurgents following a mission gone wrong and nearly executed before the team rescues her. Following this, she transfers to the OSP, becoming its newest addition until the following season. (season 11 onwards; recurring seasons 10–11)
• Devin Roundtree (Caleb Castille) is an NCIS Special Agent. Formerly with the FBI, Roundtree runs into the OSP team during season 11 after being compromised by several dirty colleagues. Following this, he later accepts an offer to try out for an opening on the team. After a few cases, he completes FLETC training and joins the OSP at the start of season 12, becoming its most recent addition. (season 12; recurring season 11)

• Indira G. Wilson/Aunjanue Ellis as Michelle Hanna aka "Quinn" (seasons 3–8): Sam Hanna's wife, Michelle is a former deep-cover CIA operative. At the end of the eighth season, Michelle is kidnapped and murdered by Tahir Khaled in a vendetta against Sam.
• Rocky Carroll as Leon Vance, the Director of NCIS (seasons 1–3, 6): He initially spent a great amount of time "getting the new LA office up and running", but still returns to ensure the well-being of his agents. Carroll also appears on both NCIS (as a regular), and NCIS: New Orleans.[14][15] He makes a seventh appearance in "Hunted". Vance appears in the season two finale and season three premiere. He makes his tenth appearance during season six.
• Brian Avers as Mike Renko, an agent attached to NCIS's Los Angeles satellite office (seasons 1, 3): He often works with OSP. An undercover operative, Renko later reported directly to Owen Granger. The team were fond of him, so it came as a shock when he was gunned down during an operation gone awry in a revenge attack.
• Kathleen Rose Perkins as Rose Schwartz, a Los Angeles County Medical Examiner (seasons 1–4): She often assists the team on their investigations. She is incredibly quirky and develops an affinity for Nate Getz, showing great romantic interest in the psychologist.
• Ronald Auguste as Moe Dusa, a man whom Sam first came into contact with in Sudan (seasons 1–2): A "brother" to Sam, of sorts, he joins a terrorist group and assists in the kidnapping of Dom. Developing a conscience, Moe assists in Dom's escape. He is later found dead by the NCIS agents.
• Vyto Ruginis as Arkady Kolcheck, a retired Russian operative (seasons 1–present): He is friends with Callen. He considers himself to be of great assistance to the NCIS team but often brings trouble in his wake. He has a daughter, Anastasia, whom he does not know very well.
• Claire Forlani as Lauren Hunter, an NCIS Operations Manager and SSA (seasons 2–3): Taken in by Hetty as a teenager, Lauren later becomes an NCIS agent and succeeds Hetty for a short time as Special Agent in Charge of OSP. Initially adversarial, the team later warmed to Hunter. She was reassigned following Lange's return but was later kidnapped and murdered by the Chameleon. Her death has a lasting effect on Lange.
• Christopher Lambert as Marcel Janvier, a serial killer and criminal mastermind (season 3–5): When Marcel is conducting business transactions, his modus operandi is to buy the supplies for his employers and then arrange a drop-off for the merchandise. He is the primary antagonist to Callen during the show's third season and is responsible for the deaths of Hunter and Renko.
• Scott Grimes as Dave Flynn, an NCIS Special Agent (seasons 4, 8): Initially an NCIS forensic specialist assigned to the elite rapid response NCIS: Red team stationed out of San Diego, Dave later transfers to San Diego's NCIS: Cyber where he re-trains as a senior intelligence analyst.
• Erik Palladino as Vostanik Sabatino, a CIA Agent (seasons 4–5, 7–8, 10): He is arrested by the team while deep undercover. He is friends with Michelle Hanna and later joins Kensi Blye's Afghanistan team. Kensi initially believes him to be her suspect, but she later realizes he is a skilled operative and will be of great use to her. In season 8, it is revealed that Sabatino is working as part of a rogue CIA faction attempting to dismantle the NCIS team.
• Anslem Richardson as Tahir Khaled, a local warlord in Sudan (seasons 3, 7–8): A war criminal and warlord, he came into conflict with CIA agents and later NCIS agents Sam Hanna and G. Callen when they went to collect evidence about the genocide he was involved in. He is Sam's arch-enemy and began plotting revenge when Sam took his sister, Jada, from him. He is the primary antagonist of the seventh and eighth seasons, and later murders Sam's wife, Michelle, near the end of season eight. He eventually kills himself via bomb in a last (failed) attempt to kill Sam.
• Matthew Del Negro as Jack Simon (seasons 5, 7): Kensi's ex-fiancé, who was suspected of being a war-criminal known as 'The White Ghost'. Kensi was assigned to assassinate him in the series' fifth season.
• Elizabeth Bogush as CIA Officer Joelle Taylor (seasons 6–10): Callen's ex-girlfriend, she is introduced as a teacher at a private school before it is revealed that she is part of the rogue CIA group tasked with dismantling the Office of Special Projects. In season 9, she, with the help of Callen, Sam, and Nell, fakes her death in order to take down the group behind the rogue CIA group. The group is known as the syndicate.
• Bar Paly as Anastasia "Anna" Kolcheck, a freelance NCIS Special Agent (seasons 6–present): The estranged daughter of Arkady Kolcheck, she is a prospective ATF agent who begins filling in on NCIS missions while Kensi is on medical leave. Following Kensi's return, Anna embarks on a relationship with Callen and joins NCIS as a Special Agent on a freelance basis.
• John M. Jackson as A. J. Chegwidden, a retired Rear Admiral and the former Judge Advocate General of the Navy (seasons 8–9): A wartime confidant of both Hetty and Granger, Chegwidden served in Vietnam as a Navy Seal. He reenters the NCIS fold at Lange's behest during an investigation into the CIA. Jackson previously appeared as Chegwidden in nine seasons of JAG, and in one episode of NCIS.
• Andrea Bordeaux as Harley Hidoko, NCIS Special Agent (season 9): Executive Assistant to EADPAC Mosley. She starts off as fiercely loyal to her boss, but soon forms a friendship with the rest of the OSP team. At the end of the ninth season, Hidoko goes missing during an off-the-books mission in Mexico to rescue Mosley's son, and is revealed to have been captured and murdered by a cartel allied with Mosley's criminal ex-husband. Her remains are identified at the end of the tenth season premiere.
• Jeff Kober as Harris Keane (seasons 9–10): A soldier who served in the CIA contingent led by Hetty and Granger in the Vietnam War. Keane was captured by Viet Cong and held captive for decades until he was rescued along with Hetty by the NCIS LA team.
• Esai Morales as Louis Ochoa, NCIS Deputy Director (season 10): Ochoa temporarily takes over directing the team in Hetty's absence.
• Peter Jacobson as Special Prosecutor John Rogers (season 10): Rogers arrives at the Los Angeles office to investigate the team, but soon gets pulled into helping them out on their operations.
• David James Elliott as Harmon "Harm" Rabb Jr. (seasons 10–11), a Naval Captain transferred from the Judge Advocate General to the USS Allegiance. Elliot reprised his role from JAG.
• Catherine Bell as Sarah "Mac" Mackenzie (seasons 10–11), the former commander of Joint Legal Services Southwest who now acts as the Marine Corps liaison to the U.S. Secretary of State. Bell reprised her role from JAG.
• Kayla Smith as Kamran Hanna (season 12), Sam Hanna's daughter. The role was originally played by Layla Crawford (guest season 3, 4, 6, 8).[16]

• Louise Lombard as Lara Macy; a former Military Police Lieutenant and the Supervisory Special Agent of OSP, Macy was relieved of her position sometime between the pilot episode and the beginning of season one. Hetty remarks she was sent to Djibouti in retaliation for insubordination regarding budget, although the truthfulness of this is unknown. After a short time working with an NCIS satellite division, Macy is found dead in an NCIS episode, murdered as part of a vendetta against Washington Special Agent Leroy Jethro Gibbs. Lombard was not picked up as a regular in the new series and the character was killed in the NCIS episode "Patriot Down".[17][18][19]

"Identity", the series' first episode, garnered 18.73 million viewers with a 4.4/11 share in the 18- to 49-year-old demographic and therefore won its timeslot. It was the second-most-watched show of the week, behind only the original NCIS.[22]

Reviews for the show have been mixed. It has a score of 59/100 on Metacritic. According to Mary McNamara of the Los Angeles Times, "The crime is intriguing and multifaceted, its resolution requiring a nice balance of street smarts and lots of gunfire. But as with the original "NCIS", the emphasis is on the characters of the team... Los Angeles, meanwhile, looks fabulous, a pleasing mixture of noir and gridlock, and there's an air of stability that's comforting in these uncertain times."[23] The New York Daily News reviewer, David Hinckley, was more critical of the show saying that although "It all adds up to an hour of decent entertainment, and there's room for enough character development to give "NCIS: Los Angeles" a personality of its own, ... a premiere episode shouldn't feel even a little like something we've already seen."[24]

Tom Shales of The Washington Post felt that, "NCIS: Los Angeles gets the job done ... It's a procedural that follows strictly the established procedure, but it has likable characters, dislikable bad guys and the occasional flabbergasting shot of L.A."[25] Robert Bianco of USA Today summarized it as a "serviceable hour that takes the NCIS formula—a light tone and a lot of banter wrapped around a fairly rudimentary investigatory plot—and transfers it to a special, undercover NCIS division in Los Angeles. Nothing more, but also nothing less."[26] The Hollywood Reporter compared the show to The A-Team with "the same lighthearted approach to life-or-death situations. Maybe the biggest change is that 'NCIS: L.A.' achieves its inevitably favorable outcomes with a little more intellect and a little less testosterone."[27] IGN stated that although "NCIS: Los Angeles doesn't exactly reinvent the police procedural... it's another above-average entry, aided by the fact that the people behind the show know what they're doing" and ultimately gave the episode a 7.7/10.[28]

Seasonal rankings (based on average total viewers per episode) of NCIS: Los Angeles on CBS.

Note: Each U.S. network television season starts in late September and ends in late May, which coincides with the completion of May sweeps.