* ActorAllusion:
** The shot of an aircraft carrier passing beneath a bridge that was used in early seasons' opening credits is from ''Film/ThePresidio'', a film Mark Harmon starred in.
** In one episode, Gibbs is asked what Ducky looked like when he was younger. He responds, "Illya Kuryakin," who was David [=McCallum=]'s character in ''Series/TheManFromUNCLE'' 40 years earlier. Later proven true in a Ducky flashback in season 12 where Adam Campbell as young Ducky is a dead ringer for [=McCallum=] during that era. Young Ducky even had Illya Kuryakin's turtleneck shirts!
** Gibbs once asked Tony for help with the crossword puzzle clue "TV Drama" and Tony answers "Series/StElsewhere," which Mark Harmon appeared on.
** Tony once says "I've got a better chance of hooking up with Jessica Alba than these guys do of infiltrating Sea Lift." Michael Weatherly was engaged to Jessica Alba for a time. He also starred with her in ''Series/DarkAngel'', where they kept trying to hook up.
*** In the episode ''Obsession'' (7x21), Tony obsesses over a journalist who embodies all what he finds attractive in a woman, and who is missing. When calling her at her cell phone, he says: "It would seem strange, but I feel like I know you". It's not so strange, though: the journalist is played by Ashley Scott, who also played underground operative and potential secondary love interest Asha Barlow in ''Series/DarkAngel''.
** Harmon's turn as SerialKiller Ted Bundy (in the TV movie ''The Deliberate Stranger'') is referenced by Fornell in the episode "Smoked" (4x10).
--->'''Fornell:''' I was on the team that nailed Bundy, Gibbs. And I'm familiar with sick, charming bastards.\\
'''Gibbs:''' That's probably why we get along so well.
*** Other references to the Bundy role include the episode where Gibbs kept getting mistaken calls about a Volkswagen Bug for sale. This was Bundy's preferred car.
** In the season eight double episode "Enemies Foreign/Domestic" (also the name of an episode of ''Series/TheWestWing'' in which Harmon appeared) Tony makes a reference to ''Series/TheWestWing'' by calling [=McGee=] [="McBartlet"=]. Both Mark Harmon and Michael O'Neill (who guest stars in these episodes) played secret service agents on the show.
** A combination of ActorAllusion and ShoutOut: Tony (Mike Weatherly)'s father is played by Robert Wagner. Weatherly met ''NCIS'' producer Donald Bellisario while Weatherly was filming ''The Mystery of Natalie Wood'', in which he played Wood's husband...Robert Wagner.
** In the Episode 'Light Sleeper' while on stake out Tony is reading an entertainment magazine
--->'''Tony:''' Damn, I can't believe this... Mick and Jessica broke up, I'm always the last to know.
:::This is just after Michael Weatherly and Jessica Alba broke up.
** A retroactive one: Early in Season 7, a Metro detective who annoys Gibbs is described as having "tugged on [[WesternAnimation/JusticeLeagueCrisisOnTwoEarths Superman's]] cape".
** In the Season 9 episode "Newborn King", Jimmy Palmer, when explaining that his future father-in-law, Ed Slater, is visiting the NCIS building, he mentions that the first time he learned that Palmer was marrying his daughter, "[Ed Slater] laughed, and then he cried from laughing too hard". Ed Slater is played by Larry Miller, who himself used the phrase "I laughed, I cried" during his first IsThisThingStillOn moment as Principal Jindrake in the movie ''Film/MaxKeeblesBigMove''.
** In season five's "Recoil", Creator/NickChinlund guest-starred as a detective hunting a serial killer who murdered women and cut off their fingers. Sixteen years earlier, he played Donnie Pfaster on ''Series/TheXFiles'' -- as a serial killer who murdered women and kept their fingers.
** Ziva's codename in "Blowback" is 'Series/DarkAngel'.
** Season 9 introduces Dr. Samantha Ryan (played by Jamie Lee Curtis) as a psychologist and love interest for Gibbs. This is a reference to ''Film/FreakyFriday'' in which she played a psychologist, frustrated with the fact that her unruly teenage daughter refuses to accept her fiance--named Ryan, played by Mark Harmon.
** In the PoorlyDisguisedPilot for Series/NCISNewOrleans, the New Orleans ME asks Gibbs if he knows anything about [[UsefulNotes/CollegiateAmericanFootball college football]]. He says no. In real life, Mark Harmon was a starting quarterback for UCLA.
** Throughout her time on the show, Jenny and Gibbs frequently flashbacked to their romance. Mark Harmon (Gibbs) and Lauren Holly (Jenny) starred together on ''Series/ChicagoHope'', where their characters had a similar relationship.
** In "Loose Cannons", it's mentioned that [=McGee=] is a Navy brat who lived in Japan for a while. One of Sean Murray's earliest roles was a US Navy Ensign stationed in Japan in ''{{Series/JAG}}''.
** A season 13 episode is titled "Reasonable Doubts", the name of an early 90's TV show Mark Harmon starred in. Furthermore, Gibbs knows sign language, as did his character on the other show.
* AdoredByTheNetwork: Creator/USANetwork will run marathons of this 2-3 days a week.
* BackedByThePentagon: The Navy and USMC support the show because malfeasance (regardless of whether it is done by service members or otherwise) is '''always''' brought to justice. In "Child's Play" season 7 episode 9, NCIS Agent Ray, who lost in checkers to the child prodigy, was played by Ray Mabus, the current Secretary of the Navy.
* BeamMeUpScotty: Abby is repeatedly misquoted as having screamed "Stop looking up my skirt!" in "Bloodbath". What she actually says is "And ''don't'' look up my skirt!"
* CaliforniaDoubling:
** A few episodes make reference to Shenandoh National Park, but the terrain and scenery don't match the real thing.
** One episode has them in a trailer park in Arlington, Virginia, an area with no trailer parks.
** The season six finale features scenes at an airfield in Israel clearly shot at Sacramento. Look for the USCG Hercules behind Ziva at the end.
** In another episode, where Tony pretends to be a convict to trace artifacts smuggled out of Iraq, they end up in a storage facility across the street from the [=WalMart=] in Lynchburg, VA; such a facility doesn't exist.
** Another episode has members of the team follow a lead in Arizona. In clear view behind them when talking to a local cop, KirksRock.
** An episode from season 9 ends with the team racing to a football stadium to stop an attack on some high ranking military members in attendance. The overhead shot of the stadium is of [=EverBank=] Field, which is in Jacksonville, Florida.
** In one episode they mention that you have to supply a fingerprint to get a drivers' license. NCIS is supposedly located in the Washington, D.C., Navy Yard. California requires a fingerprint to be issued a drivers' license. The District of Columbia, Maryland, West Virginia and Virginia do not require or ask for a fingerprint, and they are the only drivers' licensing issuing jurisdictions within 50 miles of NCIS headquarters.
** One episode features Gibbs and Ziva driving down a wide boulevard with steep-sided hills covered in dried grass and rock outcroppings in the near background. Such hills are common in the Los Angeles basin, but would be much further away and covered in trees in Virginia where the episode is supposed to take place.
** The team is often seen canvasing the scene of a crime somewhere in [=DC=] or the surrounding area. Anyone who knows [=DC=] will know that there are absolutely '''''NO''''' bridges with art deco style decorations. Los Angeles, however, is littered with them.
* TheCastShowoff:
** When some kids overthrow their football near a crime scene, Gibbs, before returning it, tells one of the kids to go long, and then he throws a perfect spiral. Keep in mind, Mark Harmon was a starting quarterback for two years with the UCLA Bruins and his father was actor and quarterback Tom Harmon, who was the first Michigan Wolverine to win the Heisman Trophy. Another bit that can be related to this is why Gibbs makes boats: Mark Harmon was a carpenter once before he started acting.
** Coté de Pablo did theater and musicals before joining ''NCIS'', and gets to show off her singing chops in "Last Man Standing", when Ziva [[http://www.youtube.com/watch?v=zX0gDdZFiJ4 performs a rendition]] of Music/TomWaits' "Temptation" while undercover as a singer in a Moroccan nightclub. The song is included on the 2-disk ''NCIS'' soundtrack album.
* CastingGag: Anthony [=DiNozzo=], Sr. is played by Robert Wagner, who was cast because Michael Weatherly played him in a Natalie Wood biopic. Commenters noted how eerily perfect the casting of Senior was, because Wagner and Weatherly share more than a passing resemblance and Wagner puts in an incredible amount of effort to show how Tony got his character tics from his father.
* CastTheExpert:
** Pauley Perrette studied sociology and criminal science before becoming an actress and playing forensic specialist Abby Sciuto.
** An interesting inversion with David [=McCallum=], who knew nothing of pathology when he was cast as Ducky, but developed such an expertise over the years in his studies for the role to make Ducky as spot on to real coroners that the showrunners were considering paying him a consulting fee.
* TheCharacterDiedWithHim: With Ralph Waite dying, Jackson Gibbs died as well. It happened in "Honor Thy Father."
* ColbertBump: Prior to the series airing, real NCIS agents referred to themselves as the [[Creator/RodneyDangerfield Rodney Dangerfields]] of law enforcement because the agency was so obscure they couldn't get any respect. Once the show became a hit, people knew what the agency did and news reports stopped saying "Naval investigators" and actually referring to the agency as "NCIS" or "Naval Criminal Investigative Service".
* CreatorBacklash: Not against the show itself, but Pauley Perrette is very vocal about how much she hates the fake spider web tattoo she has to wear on her neck, saying that it gets sticky very quickly and needs constant touch-ups. She says that if she knew in advance about all the trouble it would have caused her, she would never have agreed to the suggestion in the first place.
* DawsonCasting: Despite Abby's age being mentioned as mid-late 20s throughout the series, Pauley Perrette was born in 1969 making her about 10 years older than the character.
* {{Defictionalization}}: Theakston's Christmas Ale. Theakston was already a real brewery, but they didn't make a specific Christmas beer - until ''NCIS'' fans started inquiring about it.
* DirectedByCastMember: Michael Weatherly directed Season eight episode "One Last Score" and Season 10 episode "Seek".
* DyeHard: Pauley Perrette is a natural blonde but dyes her hair black to play Abby (occasionally using black powder to hide her roots for when she's too tired to dye them). The cumulative effects of dyeing her hair for so long caused her to have a severe allergic reaction that made her face swell up like a balloon. The left side of her face is noticeably puffy in the early episodes of Season 12.
* EditedForSyndication: At least in daytime UK screenings,for gore and violence rather than for timing.
* ExecutiveMeddling: Invoked by [[Creator/MarkHarmon Mark Harmon]]. [[Creator/DonaldPBellisario Donald P. Bellisario]] was practically untouchable due to his track record of successful TV series but his controlling nature made production a nightmare for the cast and crew (see TroubledProduction below). Mark Harmon told CBS executives that he'd walk if they didn't do anything about it and the execs decided to force out Bellisario and bring in Shane Brennan as the new showrunner. Considering that ''NCIS'' hit number one soon afterwards, this is a case of executive meddling working out for the better.
* FakeNationality:
** Coincidentally, the in-series siblings Ziva and Ari. The Israeli Mossad agent Ziva is played by Chilean actress Cote de Pablo, and the Israeli/Palestinian double agent Ari is played by German actor Rudolf Martin.
*** Most of the Israeli characters, Mossad or otherwise, on the show are not played by Israeli actors. However, notable exceptions include Sarai Givaty (Mossad Officer Liat Tuvia in "Enemies Foreign/Enemies Domestic"), Eli Danker (Mossad Officer Michael Bashan in "Shalom"), and Creator/OdedFehr (Ilan Bodner).
** Director Thomas Morrow is portrayed by Alan Dale, who is from New Zealand.
** Subverted with British actor Creator/JamieBamber as Jake Malloy (Bamber has American ancestry and citizenship despite being born in London, as his father is an American).
* FandomNod: In the season 9 episode "Life Before His Eyes," Gibbs has a near-death experience and during it he imagines what his life would be like if several things had gone differently. In his alternate timeline where [[spoiler: Kate didn't get killed by Ari]], Ziva never came to join NCIS and instead gets arrested for terrorism. Tony is the one to interrogate her, and "guesses" her name wrong several times. One of the names he calls her is "Tiva", which is the online PortmanteauCoupleName given to the Tony/Ziva ship.
* FanNickname:
** [[DopeSlap The "Gibbs Slap"]], [[AccidentalMisnaming McNicknames]], and 'autopsy gremlin' for Palmer.
*** "Gibbs Slap" and "Gremlin" for Palmer are actually used in the series. For the latter, Gibbs even mentions that they [[Film/{{Gremlins}} shouldn't get Palmer wet, or feed him after midnight.]]
** Alison Hart, the character played by Rena Sofer for a few episodes of season seven, was referred to by some fans as "Bitchy [=McLawyer=]."
** Tony used [=McNickname=] when referring to something he said NOT being one.
* HarpoDoesSomethingFunny: Gibbs simply glaring as other characters have one-sided conversations wasn't something the writers came up with. It was Mark Harmon choosing not to say his lines at all and simply use facial expressions to react to information being given to Gibbs. It quickly became a hallmark of the show and certainly made watching InfoDump scenes a lot more enjoyable.
* InMemoriam: The Season 11 finale, "Honor Thy Father", in which Jackson Gibbs dies off-camera, is dedicated to his actor, Ralph Waite, who died three months before the episode aired.
** The German dub paid tribute to Ducky's previous German voice actor in early February 2014.
** "Privileged Information", the third episode of season 14, is dedicated to showrunner Gary Glasberg, who died days prior in his sleep.
* LifeImitatesArt: [[Recap/NCISS14E12 "Off The Grid"]]'s Big Bad was an anti-government militiaman who hid his true nature so well he became a member of the Energy department just so he could get his hands on nuclear waste to make a dirty bomb. It's [[FunnyAneurysmMoment somewhat less funny]] now that [[https://en.wikipedia.org/wiki/Cabinet_of_Donald_Trump the head of the EPA wants to severely restrict the department (if not get rid of it altogether), added pictures of coal mining and removed references to climate change on the EPA website, the Secretary of Energy wanted to eliminate the department before knowing what it actually did, the Secretary of the Interior thinks lead bullets are fine for the environment, the Secretary of Education prefers private and charter schools to public schools, and the Secretary of Housing and Urban Development flat-out admitted he had no experience in that department]].
* MeanCharacterNiceActor: Harmon is nothing like Gibbs--for starters, he's a relentless practical joker, according to his costars.
* ThePeteBest: Robyn Lively played Special Agent Vivian Blackadder in the two-part ''Series/{{JAG}}'' PoorlyDisguisedPilot. Donald Bellisario reportedly said she was "too soft" for the new show, and she was replaced by Sasha Alexander's Caitlin Todd for the series proper.
* PlayingAgainstType: Believe it or not, Creator/MarkHarmon was primarily known for playing quippy smartasses before playing the functionally mute Leroy Jethro Gibbs.
* PromotedFanboy: Jon Cryer has said that he was a fan since the beginning[[note]]Both shows started in September 2003[[/note]]. After the end of Series/TwoAndAHalfMen, Cryer now has a recurring role as [[TheMedic Dr. Cyril Taft]].
* RealLifeRelative:
** Sean Murray, who plays [=McGee=], is the real-life stepson of the show's creator Donald Bellisario.
*** [=McGee=]'s sister is played by his real-life stepsister.
** In one season 9 episode, Abby shows the others a locket containing a picture of her mother. The picture is of Pauley Perrette's real-life (deceased) mother, Donna. The lock of Abby's mother's hair inside the locket was also that of Pauley's mother.
** The young Gibbs is played by Mark Harmon's son Sean.
* RealitySubtext: Creator/MarkHarmon's father was a World War 2 fighter pilot. So was Gibbs'.
* SeparatedAtBirthCasting: Compare [[http://ia.media-imdb.com/images/M/MV5BMTEwMzM3MjE2NDZeQTJeQWpwZ15BbWU3MDY4NzY3MTM@._V1_SX214_CR0,0,214,317_AL_.jpg David McCallum in his Illya Kuryakin days]] (the mid-1960s) with [[http://www.imdb.com/media/rm1056621824/tt4012538?ref_=ttmi_mi_all_sf_12 Adam Campbell as a younger version of McCallum's character]] in a season 12 episode (mid-2010s).
* SleeperHit: ''NCIS'' is one of the rare examples of a show that's steadily increased its viewing audience as it's gone on, and to continuously do it over a decade is virtually unheard of; nearly every successive season has had an episode that set a new benchmark for the show's viewership[[note]]with only seasons 4 and 5 unable to turn the trick[[/note]], with Season 10's "Shiva" the current record holder at over 22 million viewers.
* TheOtherDarrin: Because Kelly's a PosthumousCharacter and her appearances are few and far between, multiple actresses have had to portray her.
* ThoseTwoActors: Five, rather. Rocky Carroll (Leon Vance), Lauren Holly (Jenny Shepherd), Creator/MarkHarmon (Leroy Jethro Gibbs), Stacy Edwards (Dr. Janice Byers of [=S2E8=] "Heartbreak") and Jayne Brook (Lyndi Crenshaw of [=S4E20=] "Cover Story") all had starring roles on ''Series/ChicagoHope''. To top it off, Harmon and Holly's characters had a romantic relationship on this show as well.
* ThrowItIn: Gibbs' famous DopeSlap resulted from Harmon genuinely giving one to Weatherly, who he felt was goofing off too much while filming a scene (ironically, the very reason Gibbs usually gives them to people). TPTB thought it was hilarious and encouraged Harmon to make it a character tic. In true Harmon style, he gives the credit to ''Weatherly'' for not breaking character or stopping the scene.
* TroubledProduction:
** When Donald Bellisario was showrunner, he exercised tight control over the show and continuously rewrote scripts, resulting in pages being delivered just before cameras were supposed to roll and the cast and crew working longer and longer hours because of the resulting delays[[note]]According to Mark Harmon, the cast and crew of [=NCIS=] operated without ever having received a complete script for the first four seasons[[/note]]. This also led to Sasha Alexander leaving the show[[note]]she couldn't handle the thought of having to work 16 hours a day to shoot an entire network TV season[[/note]]. While this isn't unusual in TV production, Mark Harmon finally decided to put his foot down and threatened to quit unless someone else was brought in as showrunner, leading to Bellisario being forced out and Shane Brennan taking over. While this smoothed out the production process (with whole scripts now being delivered 10 days in advance of shooting), Bellisario is now in a messy and ugly legal battle with CBS over royalties.
** When Cote de Pablo's contract ran out after Season 10, she entered into protracted negotiations. While the powers that be said they kept on increasing their offers, de Pablo was hesitant to accept and dragged talks out through the hiatus before deciding to leave a week before production on Season 11 was supposed to start. This left the writers with little time to put together a workable departure for Ziva, including resolving eight seasons worth of UnresolvedSexualTension with Tony, resulting in a rushed two-episode story. Some cast members publicly expressed displeasure at how the actress left (Mark Harmon being particularly backhanded during an appearance on Arsenio Hall).
* WhatCouldHaveBeen:
** Production notes from the show say that the plan was to develop a romantic relationship between Kate and Tony--the events of the Season 3 episodes "Under Covers" and "Boxed In" would have forced them to realize that they had feelings for each other. Sasha Alexander's decision to leave the show after two seasons prevented that potential arc from happening. It's touched upon in the show's 200th episode where, in an alternate reality, Tony and Kate marry and start a family while Kate continues to be exasperated at Tony.
** Vivian Blackadder as a member of the NCIS team in the pilot, before she was replaced by Kate. Donald Bellisario thought that the Robyn Lively was too "soft" for the show.
** Scott Bakula (of ''Series/NCISNewOrleans''), Don Johnson, and ''Creator/HarrisonFord'' were among those considered for the role of Gibbs.
** Lauren Holly auditioned for--and apparently really wanted--the role of Caitlin Todd. It isn't clear if TPTB thought she'd be better for the role of Jenny Shepherd or offered it to her as conciliation.
** Another possible contender for the role of Kate? ''Creator/JenniferAniston''. Apparently, she wanted the part so much that she asked TPTB to hold off on the show until she was finished with ''Series/{{Friends}}'' (which was beginning its final season when NCIS began).
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