NCIS is an American action police procedural television series, revolving around a fictional team of special agents from the Naval Criminal Investigative Service. The concept and characters were initially introduced in two episodes of the CBS series JAG (season eight episodes 20 and 21: "Ice Queen" and "Meltdown"). The show, a spin-off from JAG, premiered on September 23, 2003, on CBS. To date it has aired sixteen full seasons and has gone into broadcast syndication on the USA Network. Donald P. Bellisario and Don McGill are co-creators and executive producers of the premiere member of the NCIS franchise. As of 2019, it is the second-longest-running scripted, non-animated U.S. primetime TV series currently airing, surpassed only by Law & Order: Special Victims Unit (1999–present), and is the 7th-longest-running scripted U.S. primetime TV series overall.

NCIS was originally titled Navy NCIS; "Navy" was later dropped from the title as it was redundant (the "N" in "NCIS" stands for "Naval"). In season six, a two-part episode led to a spin-off series, NCIS: Los Angeles. A two-part episode during the eleventh season led to a second spin-off series, NCIS: New Orleans. While initially slow in the ratings, barely cracking the Top 30 in the first two seasons, the third season showed progress, consistently ranking in the top 20, and by its sixth season, it became a top five hit, having remained there since. In 2011, NCIS was voted America's favorite television show in an online Harris Poll. The series finished its tenth season as the most-watched television series in the U.S. during the 2012–13 network television season. NCIS was renewed for a seventeenth season on April 11, 2019, which premiered on September 24, 2019.

NCIS follows a fictional team of Naval Criminal Investigative Service Major Case Response Team (MCRT) special agents based at the Washington, D.C. field office in Washington Navy Yard.^[1] In real life, the field office is based at the nearby Joint Base Anacostia-Bolling,^[2] while the Navy Yard is home to the museum and several military commands within the Department of the Navy. It is described by the actors and producers (on special features on DVD releases in the United States) as being distinguished by its comedic elements, ensemble acting, and character-driven plots. The NCIS is the primary law enforcement and counterintelligence arm of the United States Department of the Navy, which includes the United States Marine Corps. NCIS investigates all major criminal offenses (felonies)—for example, crimes punishable under the Uniform Code of Military Justice by confinement of more than one year—within the Department of the Navy.^[3]

Whenever a crime is committed involving Navy or Marine personnel, the Washington-based Major Case Response Team — an elite arm of the Naval Criminal Investigative Service — spearheads the investigation. The team, led by laconic investigator Leroy Jethro Gibbs (Mark Harmon), has included Caitlin Todd (Sasha Alexander), Anthony DiNozzo (Michael Weatherly), Timothy McGee (Sean Murray), Ziva David (Cote de Pablo), Eleanor Bishop (Emily Wickersham), Alexandra Quinn (Jennifer Esposito), and Nicholas Torres (Wilmer Valderrama). Over the course of the series, they are further assisted by allies both foreign and domestic, including Medical Examiners Dr. Donald Mallard (David McCallum), Dr. Jimmy Palmer (Brian Dietzen), forensic specialists Abby Sciuto (Pauley Perrette) and Kasie Hines (Diona Reasonover), British intelligence officer Clayton Reeves (Duane Henry), operational psychologist and senior special agent Dr. Jacqueline Sloane (Maria Bello), and successive NCIS Directors Tom Morrow (Alan Dale), Jennifer "Jenny" Shepard (Lauren Holly), and Leon Vance (Rocky Carroll).

Prior to the launch of the first season, advertisements on CBS identified the show as "Naval CIS". By the time of the launch of the first episode, NCIS was airing under the name Navy NCIS, the name it held for the entire first season. Since the "N" in NCIS stands for "Naval", the name "Navy NCIS" was redundant. The decision to use this name was reportedly made by CBS, over the objections of Bellisario,^[4] to:

In 2011, NCIS was voted America's favorite television show in an online Harris Poll.^[6] NCIS finished its tenth season as the most-watched television series in the U.S. during the 2012–13 network television season.^[7] Diona Reasonover joined the main cast in season sixteen,^[8] following the departures of Duane Henry and Pauley Perrette.^[9] NCIS was renewed for a seventeenth season on April 11, 2019,^[10] which premiered on September 24, 2019.^[11]

From the season two episode "Lt. Jane Doe" onwards, the series began showing two-second-long black-and-white clips. These clips (called "foofs") are shown at the beginning of every segment depicting the last two seconds of that segment, a segment being the five or six portions of the show meant to be separated by commercials. In the season three premiere, "Kill Ari (Part I)", a freeze-frame shot was also used with the very end of most episodes turned into a freeze frame, as well.

It was reported in May 2007, that Donald Bellisario would be stepping down from the show.^[12] Due to a disagreement with series star Mark Harmon, Bellisario's duties as showrunner/head writer were to be given to long-time show collaborators, including co-executive producer Chas. Floyd Johnson and Shane Brennan, with Bellisario retaining his title as executive producer.^[13] In fall 2009, Gary Glasberg joined the crew and became the new "day-to-day" runner of NCIS, as Shane Brennan had to focus on his new show, the spin-off NCIS: Los Angeles.^[14] On September 28, 2016, Glasberg died in his sleep at the age of 50.^[15][16]

NCIS was renewed for a seventeenth season on April 11, 2019,^[17] which premiered on September 24, 2019.^[18]

Two episodes of JAG season 8, "Ice Queen" and "Meltdown", serve as the back-door pilot of NCIS itself.

These JAG episodes introduced Mark Harmon as Gibbs, Michael Weatherly as Tony, Robyn Lively as Vivian Blackadder, Pauley Perrette as Abby, and David McCallum as Ducky.

Patrick Labyorteaux appears on NCIS reprising his JAG role as Lt. Bud Roberts in the first-season episode "Hung Out to Dry", and in the fourteenth-season episode "Rogue" and the season fifteen episode "Dark Secrets"; Alicia Coppola returned as Lt. Cmdr. Faith Coleman in "UnSEALed", "Call of Silence", and "Hometown Hero", while Adam Baldwin returned as Cmdr. Michael Rainer in "A Weak Link", and John M. Jackson appeared as retired Rear Admiral A. J. Chegwidden in the season ten episode "Damned If You Do".

The two part NCIS episode "Legend" serves as the backdoor pilot of NCIS: Los Angeles.

"Legend" introduces Chris O'Donnell as G. Callen, LL Cool J as Sam Hanna, Daniela Ruah as Kensi Blye, and Barrett Foa as Eric Beale.

Rocky Carroll recurs on NCIS: Los Angeles as his NCIS character Director Leon Vance, while Pauley Perrette has appeared twice as Abby, and Michael Weatherly has appeared once as Anthony DiNozzo. NCIS guest stars reprising roles between series include David Dayan Fisher as CIA Officer Trent Kort, in the seasonfinale of NCIS: Los Angeles; Kelly Hu as Lee Wuan Kai in NCIS: Los Angeles and later in an episode of NCIS.

John M. Jackson has appeared on NCIS: Los Angeles as his JAG character Admiral A. J. Chegwidden, while this series has also crossed over with Hawaii Five-0 and Scorpion.

The two-part NCIS episode "Crescent City" serves as the back-door pilot of NCIS: New Orleans.

"Crescent City" introduces Scott Bakula as Dwayne Pride, Lucas Black as Christopher LaSalle, Zoe McLellan as Meredith Brody, and CCH Pounder as Loretta Wade.

Rocky Carroll recurs as Director Leon Vance, while NCIS series regulars Mark Harmon, Michael Weatherly, Pauley Perrette, Sean Murray, Emily Wickersham, Wilmer Valderrama, David McCallum and Brian Dietzen have all appeared as their NCIS characters. NCIS recurring cast members Meredith Eaton, Joe Spano, Diane Neal, and Leslie Hope have all guest-starred on NCIS: New Orleans.

NCIS airs on Network Ten and TV Hits (formerly TV1)^[21] in Australia,^{[22][23][24][25][26][27][28]} Global (syndicated on Showcase and Lifetime), TV3 and The Box in New Zealand, Seriale+ (premieres), TVN (free-TV premieres), TVN7 (reruns), AXN (reruns), (India) Fox Crime and TV Puls (reruns) in Poland, CBS Justice, Universal UK, Channel Five and Five USA in the United Kingdom, and RTÉ2 on Wednesdays at 11pm in Ireland.

The first 11 seasons of NCIS have been released in Regions 1, 2, and 4. In Germany (Region 2), seasons 1–4 and 5–8 were released in two separate sets for each season. The first-season DVD omits the two introductory episodes from season eight of JAG, though they are featured on the JAG season eight DVD.

In 2010, CBS Interactive and GameHouse released a mobile video game, NCIS: The Game for iOS, Android, BlackBerry, Windows Mobile, and BREW/J2ME. The game features five different cases written by the show's writers.^[29]

On November 1, 2011, Ubisoft released a video game adaption ofNCIS for the PC, Xbox 360, PlayStation 3, and Wii. A Nintendo 3DS version was released on March 6, 2012. The video game was deemed as a mockery of the show by reviewers and players alike, and received a 2/10 rating on GameSpot.^[30]

There's also a Facebook and mobile game called NCIS: Hidden Crimes.^[31][32]

In the UK, certain NCIS multi-part episodes were edited together to make a combined feature and shown on Channel 5, 5USA, CBS Action and Fox UK. These include:

CBS Records released the show's first soundtrack on February 10, 2009.^[47] The Official TV Soundtrack is a two-disc, 22-track set that includes brand new songs from top artists featured prominently in upcoming episodes of the series, as well as the show's original theme by Numeriklab^[48] (available commercially for the first time) and a remix of the theme by Ministry. The set also includes songs performed by series regulars Pauley Perrette and Coté de Pablo.

A sequel to the soundtrack was released on November 3, 2009. NCIS: The Official TV Soundtrack; Vol. 2 is a single-disc, 12-track set that covers songs (many previously unreleased) featured throughout the seventh season of the show, including one recording titled "Bitter and Blue" by Weatherly, as well as two songs used in previous seasons.

In 2016, The New York Times reported that NCIS "is most popular in rural areas", especially in rural Maine and Pennsylvania.^[49]

Seasonal rankings (based on average total viewers per episode) of NCIS.

NCIS has produced two spin-offs: NCIS: Los Angeles (2009–) and NCIS: New Orleans (2014–).

In November 2008, reported that a first spin-off series set in Los Angeles would be introduced with a two-part backdoor pilot during the sixth season of NCIS. The episode title "Legend (Part I)" and "Legend (Part II)", airing on April 28, 2009, and May 5, 2009.^[80][81][82] On May 2009, CBS picked up an NCIS spin-off series with the title NCIS: Los Angeles.^[83]

The series stars Chris O'Donnell as Special Agent G. Callen,^[84] LL Cool J as Special Agent Sam Hanna,^[84][85] Louise Lombard as Special Agent Lara Macy, Peter Cambor as Operational Psychologist Nate Getz, and Daniela Ruah as Special Agent Kensi Blye.^[86][87] Following the official pick-up by CBS, it was confirmed that Lombard had not been to continue her role as Special Agent Lara Macy.^[88] Linda Hunt and Adam Jamal Craig were add the cast as OSP Manager Henrietta Lange and Special Agent Dom Vail respectively.^[89] Craig, would not be returning for second season and was replaced by Eric Christian Olsen as Marty Deeks promoted to series regular.^[90]

Characters from NCIS have appeared in the spin-off. Rocky Carroll portrayed as Leon Vance in a recurring role,^[91][92][93] and Pauley Perrette portrayed as Abby Sciuto with guest appearance in the season 1 episodes "Killshot", and "Random on Purpose".^[92][93][94]

NCIS: Los Angeles was created by Shane Brennan. In April 2011, NCIS creator Donald Bellisario sued CBS over NCIS: Los Angeles because of his contract which gave him "first opportunity" to develop a spin-off or sequel,^[95] the lawsuit was dismissed by a judge in June 2012. However, discussions continued between CBS and Bellisario and in January 2013 the dispute was settled outside of court a week before it was set to go to trial; the terms of the agreement were not disclosed but were described as being amicable.^[96][97][98]

In September 2013, reported that a second spin-off series set in New Orleans would be introduced with a two-part backdoor pilot during the eleventh season of NCIS. The episode title "Crescent City (Part I)" and "Crescent City (Part II)". The episodes were filmed in February 2014, and aired on March 25, 2014, and April 1, 2014. NCIS star Mark Harmon and showrunner Gary Glasberg are the executive producers of the series.^[99] Glasberg discussed the idea of the episode with Harmon, who said "That's more than a[n] [...] episode".^[100] The premise for the episodes are, according to Glasberg, "all about this tiny little NCIS office that's down [in New Orleans], and the kind of cases that they come across".^[101] On May 2014, CBS picked up an NCIS second spin-off series with the title NCIS: New Orleans.^[102]

The series stars Scott Bakula as Special Agent Dwayne Cassius Pride, Lucas Black as Special Agent Christopher LaSalle, Zoe McLellan as Special Agent Meredith "Merri" Brody, Rob Kerkovich as Sebastian Lund, and CCH Pounder as Dr. Loretta Wade.^{[103][104][105][106]} Daryl "Chill" Mitchell, Shalita Grant and Vanessa Ferlito joined the main cast later, portrayed as computer specialist Patton Plame, Special Agent Sonja Percy, and Special Agent Tammy Gregorio, respectively.^[107][108]

NCIS and NCIS: New Orleans have had two crossovers.

NCIS has received many awards and nominations since it premiered on September 23, 2003, including the ALMA Awards, ASCAP Awards, BMI Film & TV Awards, Emmy Awards, and People's Choice Awards.