The Naval Criminal Investigative Service (NCIS), formerly the Naval Investigative Service (NIS)) is a U.S. federal law enforcement agency charged with conducting investigations of felony-level offenses affecting the U.S. Navy and U.S. Marine Corps – that is, crimes punishable by confinement for more than one year. NCIS also performs investigations and operations aimed at identifying and neutralizing foreign intelligence, international terrorist, and cyber threats to the U.S. Department of the Navy. In addition, it provides warning of threats and specialized defensive force protection support to U.S. naval forces around the world.
- Erica Jane Barrett- A NCIS Special Agent and the former leader of her own team. She lost her two team-members, Gayne Levin and Simon Cade to both Jonas Cobb, the Port to Port killer and Jonathan Cole, a murderer respectively. When she first joined NCIS, she had something of a romantic relationship with Anthony DiNozzo. She later went on the run, having been fingered for assassination by Cole himself who attempted to kill Barrett and DiNozzo but failed. Once Cole was finally arrested, she emerged and headed off to her parent's house for a long rest.
- Eleanor Bishop- A NSA agent who has joined NCIS as a liaison and who is also former Mossad Liaison/NCIS Special Agent Ziva David's replacement.
- Vivian Blackadder- A former FBI-turned-NCIS Agent, Viv joined NCIS after the USS Cole bombing which killed her brother, Rex. Her primary goal for coming to the agency was to get revenge for his death although this caused her to clash with Leroy Jethro Gibbs. She was DiNozzo's partner but blew an important anti-terrorist operation which resulted in her being either fired or returning to the FBI of her own free will. Current fate unknown.
- Kensi Blye- A NCIS Special Agent who is a member of the Office of Special Projects which specializes in undercover work and is located in Los Angeles. Her father is a Marine who was murdered by a member of his own unit and the crime remained a cold case for fifteen years until it was finally solved in February 2012.
- Stanley Burley- A NCIS Special Agent who worked under Gibbs and was also Agent Afloat on the USS Enterprise. Eight or nine years later, he returned to help Gibbs and the team in regards to Harper Dearing.
- Simon Cade- A member of Special Agent E.J Barrett's team who survived an ambush by Jonas Cobb which resulted in the death of Cade's colleague, Gayne Levin. Cade was later killed at the hands of Jonathan Cole who attempted to frame DiNozzo for the crime.
- G. Callen- An NCIS Special Agent assigned to the Office of Special Projects in Los Angeles who is also the leader of the field team there. Was arrested for killing the Chameleon who had murdered Agents Mike Renko and Lauren Hunter but it was later revealed that the Chameleon's death had been faked. After he and Callen were returned to their respective sides in a prisoner exchange, Callen returned to lead the OSP team once again.
- Paula Cassidy- An NCIS Special Agent who worked at Guantanamo Bay as an interrogator and later became the leader of her team who worked from the Pentagon. She and Anthony DiNozzo had something of a romantic relationship that Cassidy herself later ended. Following Agent Caitlin Todd's death at the hands of rogue spy, Ari Haswari, Cassidy was temporarily assigned to Gibbs's team in the Season 3 episode, Mind Games (episode), resulting in her becoming DiNozzo's partner. Returned in the Season 4 episode, Grace Period (episode) after her team were killed by a suicide bomber. She later died after sacrificing herself to stop a suicide bomber, saving the lives of Agent Leroy Jethro Gibbs and his team.
- Jerome Craig -- Deputy Director of NCIS, and second in command to Leon Vance who became Acting NCIS Director after Leon Vance stepped down following the death of Vance's wife, Jackie.
- Ziva David- An Israeli working for Mossad who could speak 10 languages and who joined the Major Case Response Team on a permanent basis after her predecessor, Agent Caitlin Todd was brutally murdered at the hands of Ziva's half-brother, Ari Haswari. After Ziva was proved wrong by Gibbs that Ari did kill Special Agent Caitlin Todd, Ziva proved her loyalty by killing her half brother, Ari, to save the life of Special Agent Gibbs. For four or five years, Ziva worked at NCIS, having assigned to the team as a Mossad Liasion Officer for NCIS until the death of her boyfriend, Michael Rivkin at the hands of her partner, Anthony DiNozzo which prompted Ziva to rejoin Mossad and begin working for her father once again. Months later, it was revealed that Ziva was missing, presumed dead although she had actually been captured by the terrorist, Saleem Ulman and was being tortured for information. DiNozzo, Gibbs and Timothy McGee were successful in saving her. Having returned to the U.S, Ziva later resigned from Mossad for good and later became an NCIS Special Agent as well as an official American citizen. Her speciality is performing assassinations. In the Season 10 finale episode, Damned If You Do (episode), Ziva along with Tony and McGee resigned from NCIS to protect Gibbs. While Tony and McGee remained in the U.S., Ziva returned to Israel but later went into hiding after learning that she and her colleagues were targets of a group called the "Brotherhood of Doubt" with her final appearance being in the Season 11 episode, Past, Present and Future (episode) where after kissing Tony, she opted to stay behind in Israel rather than return to the U.S.
- William Decker- A retired NCIS Agent who along with Agent Leroy Jethro Gibbs and future NCIS Director Jenny Shepard belonged to a team assigned to kill a Russian arms dealer and his fianceé in Paris nine years previously. Decker later retired from NCIS before being murdered with his death disguised to look like he had suffered a heart attack. He died protecting Gibbs and Jenny but the events that had cost him his life also led to Jenny's death.
- Anthony DiNozzo- A former Detective working at Baltimore, DiNozzo later joined NCIS after realizing his partner was a dirty cop. Was a witness to his partner, Agent Caitlin Todd being killed by Ari Haswari and was also responsible for the death of Mossad Officer Michael Rivkin. Is the longest-serving Agent on Gibbs's team and often uses his title of Senior Field Agent to force others to do tasks he doesn't want to do, a tatic that sometimes works against him. Despite his childish personality, DiNozzo is very sharp and does express concern for the other members of his team. His speciality is undercover work.
- Don Dobbs- An NCIS Special Agent who participated in the investigation into the murder of Lieutenant Loren Singer in the JAG episodes "Ice Queen" and "Meltdown". Current fate unknown.
- Chad Dunham- A Special Agent assigned to the Horn of Africa who appeared in three episodes of Season 7.
- Bryn Fillmore- A temporary replacement for Ziva David. She resigned from the team with her resignation letter which apparently took her a month to write up, describing DiNozzo and McGee as "annoying", "childish" and "Sidekick". Current fate unknown.
- Michael Franks- Was the head of the Major Case Response Team and is also responsible for helping Gibbs, a former Gunnery Sergeant become an official NIS/NCIS Special Agent. Franks later retired and gave Gibbs official command of the team. After retiring, Franks moved to Mexico and regularly returned to the U.S to help Gibbs and the team during some investigations. Was killed by Jonas Cobb, the Port to Port killer, leaving the team devastated.
- Leroy Jethro Gibbs- A former Marine Sniper/Gunnery Sergeant in the United States Marine Corps who is now the current head of the Major Case Response Team working out of Washington D.C. He has something of a gruff personality, has had three failed marriages and a strong love for coffee. His first marriage ended tragically when his first wife and their young daughter were killed by a drug dealer who Gibbs later killed in revenge. Gibbs's speciality is long distance range shooting, a skill he inherited during his days in the Marines and one that has come in handy on occasion.
- Owen Granger- An Assistant Director of NCIS who currently oversees the Office of Special Projects in Los Angeles.
- Rick Hall- A member of Paula Cassidy's team who died in a suicide explosion in Grace Period (episode).
- Sam Hanna- A former Navy SEAL who works for the Office of Special Projects and is fluent in Arabic. He is G. Callen's partner and is married with a wife and a young daughter.
- Nikki Jardine- An intelligence analyst for NCIS. She is fluent in English, Arabic, and Kurdish and seemingly suffers from OCD. Has a brother named Eric who was injured in Iraq and is in a coma.
- Daniel Keating- An NCIS Special Agent assigned to Gibbs's team for four months and who was also suspected of being the mole selling state secrets. Was later transferred back to the Cyber Crimes Unit after being found innocent.
- Melora Koss- A retired NCIS Agent who attended the recent NCIS review conference orchestrated by NCIS Director Leon Vance and Mossad Director, Eli David.
- Brent Langer- Originally part of Gibbs's team, Langer later joined the FBI and was also a member of Gibbs's new team after DiNozzo, McGee and David were all reassigned to different positions. Was later killed at the hands of Michelle Lee, the real NCIS mole who had murdered Langer to presumbly make sure her cover was protected at all costs. His old FBI ID was placed on a bar wall dedicated to fallen officers and agents.
- Michelle Lee- An NCIS Agent who joined the Major Case Response Team to bring them back up to full strength after Gibbs abruptly quit. She was later transferred back to the Legal Department when Gibbs returned and in Season 6, was a member of his new team that Director Vance had personally assembled. Her role as the mole was later discovered and she began working with the other Agents in hopes of saving her daughter/sister Amanda. She later became a human hostage shield courtesy of Ted Bankston and died when Gibbs shot at both of them, essentially sacrificing herself in the process.
- Gayne Levin- A member of E.J Barrett's team who was murdered at the hands of the Port to Port killer.
- Lara Macy- An NCIS Special Agent who was the temporary head of the Office of Special Projects in Los Angeles and had a hostile relationship with Agent Gibbs. After an assassination attempt that left one of her Agents, G. Callen fighting for his life, Director Leon Vance reassigned Macy to a task force in Marseille, Bouches-du-Rhône, Provence-Alpes-Côte d'Azur, France. She was later murdered by Jason Paul Dean who was working for the Reynosa Cartel, leaving both Gibbs and the members of the Office of Special Projects shocked at her death.
- Dr. Walter Magnus- The original Medical Examiner for NCIS who was later replaced by Dr. Donald Mallard. Magnus is currently suffering from Alzheimer's Disease.
- Donald Mallard- The current Medical Examiner for NCIS. His specialty in addition to performing autopsies is composing or preparing psychological profiles of various persons of interest.
- Riley McCallister- A retired NCIS Special Agent in Charge who attended the recent NCIS review conference. It was shown that he was using a cane to aid his walking process although it is presumed that some sort of injury might be responsible for that. The conference revealed that McCallister aspired to become the Director of NCIS, and was driven to destroy or stunt the careers of those agent he perceived as threats. He is responsible for orchestrating the assassination of Director Shepard, and he attempted twice to kill Vance by rigging the safehouse Vance was in with claymore mines and the second time by injecting a lethal dose of morphine into Vance's system in hopes of finally ending Vance's life. Died as a result of the wounds he had received after Vance had stabbed him with a knife Gibbs had given him for protection.
- Timothy McGee- An NCIS Special Agent originally assigned to the Norfolk Naval Base, McGee achieved his dream of becoming a full-time Field Agent in the Season 2 episode, See No Evil (episode) and was also assigned to Gibbs's team on a permanent basis, becoming the Probie of the team, a nickname he held for six years up until Ziva David became an official NCIS Agent. McGee's speciality is operating computers or anything technology-related.
- Thomas Morrow- The first official NCIS Director seen in the series. In Kill Ari Part 1 (episode), following the death of Special Agent Caitlin Todd at the hands of Ari Haswari, Morrow resigned from NCIS to go accept the position of Deputy Secretary of the Homeland Security. Morrow was succeeded by Jenny Shepard.
- James Nelson- An NCIS Agent who along with Rick Hall was a member of Paula Cassidy's team and had a strong friendship with Agent McGee. Nelson was killed in an explosion at the beginning of Grace Period (episode). Prior to his death, Nelson had been married for two months to his wife Amy.
- Kurt Nelson- A retired NCIS Agent who attended the recent NCIS review conference.
- Richard Owens- An NCIS Agent Afloat stationed at Pearl Harbor, Hawaii who helped Gibbs and his team on a case regarding a murdered lieutenant named Lieutenant Mark Schilz who was believed to have absconded with one million dollars of stolen Navy funds in 1994.
- Christopher Pacci- An NCIS Special Agent who was friends with Leroy Jethro Gibbs. Was brutally murdered after being shot in the neck and then disemboweled with his death greatly affecting Gibbs. It was later revealed that he had been killed at the hands of Amanda Reed who had been Lt Commander Hamilton Voss before undergoing gender reassignment surgery. Gibbs later avenged Pacci by killing Reed.
- Jack Patterson- An NCIS Special Agent who was Agent Afloat on the USS George Washington. He was murdered by a professional assassin employed by an Arizona mining company based in Phoenix. Had a close personal and professional relationship with Abigail Sciuto who was left shocked by his death.
- Mike Renko- An NCIS Special Agent assigned to the Office of Special Projects in Los Angeles. In May 2012, Renko was murdered by the Chameleon, leaving his OSP colleagues devastated.
- Ben Robinson- A retired NCIS Agent who attended the recent NCIS review conference.
- Abigail Sciuto- NCIS's Forensic Scientist who wears Gothic clothing and has tattoos. Despite those traits that would make her seem anti-social or even unfriendly, she is actually very cheerful and sweet with a bubbly personality. She also has a strong loyalty towards Gibbs and his team. Her specialty is Forensic Science.
- Jennifer Shepard- A former NCIS Special Agent and Gibbs's girlfriend, Shepard later became the new NCIS Director after Tom Morrow resigned to accept a position at the Department of Homeland Security. Died from injuries sustained in a gunfight in an abandoned diner in a California desert. Her specialty was admin work. After her death, Leon Vance succeeded her by becoming the new NCIS Director.
- Whitney Sharp- A retired NCIS Agent who attended the recent NCIS review conference. She had a brief liaison with Dr. Mallard.
- Caitlin Todd- A former Secret Service Agent assigned to the Presidential Protection Detail on Air Force One, she joined NCIS after resigning from the Secret Service due to the fact that she had been in a relationship with Major Timothy Kerry which was against the rules. She spent a year and a half working as an NCIS Special Agent, improving her skills while also aiding the team in their various investigations. Her career unfortunately came to an abrupt end when in the Season 2 finale, Twilight (episode), Kate died after being shot in the head by Ari Haswari, leaving the team devastated and grief-stricken. She was eventually replaced by Ziva David. Kate's speciality was psychologically profiling the people she and her colleagues met during their investigations.
- Leon Vance- The current Director of NCIS who replaced Jennifer Shepard after she was killed in the line of duty. His speciality is admin work although he has been seen out in the field and even wielding a gun a few times.
NCIS Most Wanted
- Ari Haswari- An Israeli spy/double agent for Hamas and Mossad who first appeared in Bête Noire (episode) where he caused a hostage situation by taking Donald Mallard, Gerald Jackson and Caitlin Todd prisoner in the morgue. Shot Jackson and Leroy Jethro Gibbs in their respective left shoulders before fleeing the scene. Returned a year later in Twilight (episode) where it was revealed that he was the leader of a terrorist cell in Washington D.C. Gibbs and the team stopped an attempted attack by the cell from going ahead by storming the warehouse and killing all the terrorists except for Ari. However, NCIS suffered a devastating tragedy when Ari shot Agent Todd in the forehead, killing her instantly. Hours later, Ari then began a sadistic game, targeting the female members of Gibbs's team while having the nerve to claim that he wasn't responsible for Kate's death. Attempted to kill Gibbs in his basement before he was eventually killed at the hands of his Mossad Control Officer and half sister Ziva David.
- Mamoun Sharif- Originally from Lebanon, Sharif lost his wife and two children to an American smart bomb. This prompted him to join the CIA where he became a paid informant for the CIA, helping them to arrest a gun-smuggling ring at a U.S. military base in Turkey. As reward for his efforts, the CIA relocated him to America, and paid him a small monthly stipend all while looking to get revenge against the Americans responsible for killing his family. He faked his death and escaped being arrested. Resurfacing months later, Sharif emerged, engineering a plot to poison people with BZ nerve gas, even poisoning Gibbs in the process. He attempted to make his escape from a railway station in D.C but NCIS and the Army CID caught up to him. Sharif then attempted to kill Gibbs with his own weapon. Luckily, Colonel Hollis Mann arrived in the nick of time, killing Sharif and saving Gibbs's life as well.
- Lee Wuan Kai- An assassin originally from North Korea. Brainwashed and trained to becoming a killer from a very young age, Lee grew up to become a deadly assassin responsible for the deaths of numerous people all over the world including Leon Vance's partner. This caused Vance to develop a strong obsession with bringing her to justice. He encountered her in many places over the next few years and even encountered her in Los Angeles where he had been with the Office of Special Projects. The two eventually got into a gunfight with Lee being injured and escaping to Washington D.C which brought her into contact with OSP's counterpart, the Major Case Response Team and also had Vance searching for her again. She shot an South African-born assassin who was out to kill her and eventually died at the hands of Vance's wife, Jackie.
- Jonas Cobb- A U.S sailor who joined a CIA-led operation code-named Frankenstein and went through brutal training. The strain of what he was doing left him psychologically damaged and also led him to believe that he no longer had to obey any authority. He became a serial killer called the Port-to-Port killer who was responsible for the deaths of many sailors who made windfall. Cobb is also the one who killed Leroy Jethro Gibbs's mentor, Mike Franks and also Agents Earl Stark and Gayne Levin as well as the one who cost CIA Agent Trent Kort his left eye. He soon came to NCIS Headquarters, capturing Kort, EJ Barrett and Jimmy Palmer before holding them hostage while torturing them. SECNAV, Philip Davenport who was Barrett's uncle and backed by Gibbs and Director Leon Vance tried to get Cobb to surrender but Cobb presumably attempted to attack, forcing Gibbs and Vance to shoot him, the effects causing him to fall out of a window and onto a car which killed Cobb, finally ending his rampage for good.
- Harper Dearing- The CEO who was the leader of a terrorist cell targeting U.S. Navy ships. Launched an attack against NCIS HQ and also against the Navy in revenge for the death of his son, Evan. His regime of terror came to a permanent end when Leroy Jethro Gibbs stabbed him, resulting in Dearing's death.