The Entire NCIS Timeline Explained

Though it began as a simple, inauspicious backdoor pilot during the eighth season of "JAG," CBS's "NCIS" has ballooned into one of the biggest TV franchises ever, long outlasting the series that spawned it and now featuring multiple spin-offs and crossovers of its own. Taking a group of special agents in the Naval Criminal Investigative Service as its focus, the procedural follows the group's investigations into criminal cases involving Marine and Navy personnel and their loved ones. But it's the cast of characters that have kept many fans tuning in since 2003. With the former Marine Sniper Leroy Jethro Gibbs (Mark Harmon) leading the main series, each new show has launched its own ensemble cast for viewers to look forward to seeing with each entry.

The timeline of "NCIS" specializes in catering to fans and newcomers alike, with endless guest spots and crossovers that seldom require full knowledge of the corresponding series to enjoy. Yet, with so many episodes in the can and several spin-offs having come and gone over the last two decades, it can still be a little difficult to know quite where to begin. Fortunately, you don't have to watch every episode of "NCIS" to understand the general timeline. As sprawling media franchises go, this one is actually surprisingly straightforward, as long as you've got a nudge in the right direction.

Though "JAG" drew to a close with the final episode of its 10th season in 2005, "NCIS" was just picking up steam. While the first season explored the setting and naval themes and served to establish the tone of the series, the second leaned into developing the central cast and adding depth and backstory. It also added the dramatic two-second black and white clips, called "phloofs," which helped to establish the ongoing aesthetic of the show. Agent Todd is killed in the finale, "Twilight," leaving Gibbs on the hunt for revenge right as his ex and the new NCIS director, Jenny Shepard (Lauren Holly), arrives on the scene. We learn more about Gibbs's past, as well as his relationship with his ex-wife and their daughter.

The fourth season saw Gibbs pull back for a bit due to a preventable tragedy as DiNozzo stepped into leadership, while the fifth and sixth seasons continued to explore Gibbs's character more thoroughly and introduced some new cast members along the way. Gibbs would stay with the series until late in the 18th season, making him perhaps the most popular among "NCIS" mainstays, but characters like forensics specialist Abby Sciuto (Pauley Perrette), special agent Timothy McGee (Sean Murray), and others also made an impact due to the series showing their unique responses to their work of investigating horrific crimes. At any rate, "NCIS" remains a ratings monster today (via The Hollywood Reporter), and these were the seasons that established it as such.

With its sister show creating different vibes for the franchise, "NCIS" wrapped up the Ziva storyline from its sixth season by introducing her as an NCIS agent once she resigned from Mossad entirely, though she would soon meet a fresh challenge with Ray, a CIA agent who regularly interfered with NCIS business. Meanwhile, major revelations around Gibbs and what became of his first wife and daughter are dropped in the eighth season, with their killer playing a larger role. The ninth season largely revolves around the crew attempting to stop a terrorist attack, while the 10th sees Gibbs's leadership called into question. With Ziva gone by the 10th season's conclusion, the 11th introduces us to her replacement, Eleanor Bishop (Emily Wickersham).

Meanwhile, the Los Angeles crew keeps busy. The "odd couple" friendship between Callen and Sam takes center stage in many episodes, and the two make an unbeatable duo through these seasons as their bond strengthens. Callen's complicated and mysterious back story as an orphan, with only a vague understanding of his origins, slowly unravels while he mitigates the responsibilities that come with leadership. The 21st episode of the third season, "Touch of Death," features a crossover of the crew with Danny Williams and Chin Ho Kelly of the "Hawaii Five-0" reboot, as they team up with Sam and Callen to stop a disgruntled scientist attempting to reintroduce smallpox to the world.

No doubt you're getting accustomed to the two-part backdoor pilot formula, and that's for the best because there is another one in store. In the 11th season of "NCIS," a two-parter titled "Crescent City, Part 1 and 2" introduced the franchise's third series, "NCIS: New Orleans." When a congressman is found murdered in New Orleans, Gibbs and company are immediately involved in the investigation, reuniting long-time friends Gibbs and NCIS Special Agent Dwayne Pride (Scott Bakula), soon to lead up this faction of the "NCIS" franchise. The "NCIS" crew splits up to tackle this high-pressure case, with Gibbs and Bishop onsite and DiNozzo and McGee staying in D.C.

As "NCIS" episodes go, this one has an extra layer of the ominous added on top as the mysterious killer stalks Gibbs and the others while they attempt to track him, taking photos of them. Though the case is pure "NCIS"-flavored forensics, the New Orleans backdrop immediately gives the episodes a unique feel, which would continue in earnest in the spin-off. Though "New Orleans" would wrap after seven seasons, it tackled plenty of unique subject matter while allowing its location to step up as a character in and of itself, making for a series that lived up to the "NCIS" name while going in its own distinct direction at every opportunity.

Kicking off with the pilot episode, "Musician Heal Thyself," the "NCIS: New Orleans" introductory cast is solidified as Pride and LaSalle's (Lucas Black) established dynamic is offset by the new addition of the recently transferred Meredith Brody (Zoe McLellan). Despite this familiar "NCIS"-style dynamic, "New Orleans" delves into slightly spookier subject matter than the other two shows, with organ thieves, drug cartels, and the occasional faked death from Pride spicing things up along the way. While Gibbs and Callen are both a bit more mysterious, Pride is friendly and warm, and openly prioritizes sentimentality and doing good in a world that doesn't always live up to his expectations, granting audiences a different leadership vibe while staying true to the franchise's overall values.

"New Orleans" concluded in May 2021, but both "Los Angeles" and the original series were still going strong. By the time "New Orleans" came to a close, "Los Angeles" was wrapping its 12th season, while "NCIS" was wrapping its 18th and saying goodbye to its longtime leader, Gibbs, in favor of its new lead, Parker (Gary Cole). Regardless of its relative brevity, the "New Orleans" conclusion feels organic, with Pride getting a happy ending via a marriage to his long-time love Rita, and the feelings of family formed among his crew at the forefront. Besides, the ending of this series opened the floor for another spin-off, but more on that in a moment.

"NCIS: Hawai'i" is the only "NCIS" spin-off so far that wasn't introduced via a backdoor pilot in the main series, but there is a crossover in the first season with the "NCIS" episode "Starting Over" and "Hawai'i" episode "T'N'T." The first part of this story is fairly brief, with Torres heading to Hawai'i, but the second part features a spike in action. Torres takes a trip to Hawai'i to team up with Jane, only for them to be ambushed and the witness they're escorting killed in a shootout, with his body stolen from the scene. The episode then revolves around the agents attempting to get to the bottom of who masterminded the attack.

This all dates back to a case from Torres's past that intrigued him but at the time went unsolved, but as with all "NCIS" crossovers, the story is in the chemistry between series mainstays. Torres and Tennant make for an iconic duo, and indeed one of the running jokes of the episode is that her team is caught up trying to get to the bottom of their past together only for Torres to leave, noting that he "had fun," to which Tennant ultimately quips, "What happened in Orlando...stays in Orlando," after Torres departs. Likewise, Tennant's interactions with her team are a highlight here, showing how unique her people skills make her in the realm of the police procedural.