First, keep in mind that a series billed as "Top Gun meets A Few Good Men" was considered a tantalizing sell in 1995. So even though the NBC military drama JAG got axed after one season, programming executives at CBS understood the appeal and snatched it up. They were right, and the show ran all the way until May 2005.
More significantly, JAG also spun-off a series in 2003 titled NCIS. And on March 17, the durable police procedural will air its 500th episode, to make it one of the longest-running dramas of all time.
Created by former Marine Corps Sergeant Donald Bellisario (who also launched JAG and Quantum Leap), NCIS focuses on special agents from the Naval Criminal Investigative Service based in Washington D.C. They investigate a series of crimes connected to the Navy and Marine Corps personnel. Mark Harmon, a welcome small-screen presence by way of St. Elsewhere and Chicago Hope, originally led the team as Leroy Jethro Gibbs.
Like JAG, NCIS wasn’t a runaway hit. But by the show's third season, it was winning its time period on Tuesday nights. No matter that the network was strongly associated with the AARP-eligible crowd: NCIS attracted a younger demographic thanks to its kooky humor, overlapping dialogue, grainy black-and-white flashback sequences and a sudsy storyline involving Gibbs and his new supervisor (Lauren Holly). NCIS ultimately grew into the highest-rated broadcast drama on TV.
“I have a very strange way of writing,” Bellisario told The Television Academy in 2015. “I don’t do stories. I sit down and I start to write, and I either write to something or I write from something, and the story unfolds. That way, I am highly entertained because it’s unfolding for me the same way it unfolds for an audience.”
Bellisario stepped down in 2007; Harmon left in 2021. Many of the OGs are long gone as well. (RIP, David McCallum). And yet, NCIS remains more than a TV series — it’s now an unstoppable global entity, with several spinoffs.
In honor of the big milestone, here’s a by-the-numbers look at NCIS. Grab your gear!
The current cast of NCIS
Total Emmy nominations: 3.
Emmy wins: 0.
Number of times JAG star David James Elliott reprised his role on NCIS: 0, though his Harmon “Harm” Rabb Jr. character popped up on NCIS: Los Angeles.
Final Nielsen ranking at the end of its initial 2003-04 season: No. 23, behind the likes of American Idol, Friends and CSI.
Years it took for NCIS to reach its 100th episode: 4.
Years it took for NCIS to reach its 300th episode: 13.
Years it took for NCIS to reach its 400th episode: 17.
Full seasons that Harmon appeared onscreen as Gibbs: 18 (along with four episodes of Season 19).
Seasons that Harmon narrated the Gibbs prequel series, NCIS: Origins: 2 and counting.
Harmon’s reported salary in 2018: $19 million per season.
NCIS star Marc Harmon
Main cast members from the original season who still appear on the show: 0.
Recurring cast members from the first season who still appear on the show: 2 (Sean Murray’s special agent Timothy McGee and Brian Dietzen’s medical examiner Dr. Jimmy Palmer both appeared in Season 1 before becoming regulars).
Episodes logged by Sasha Alexander, who was the first regular cast member to exit (her Kate Todd character was killed by a sniper): 49.
Episodes logged by McCallum, who played Dr. Donald “Ducky” Mallard from the first season through his death in 2023: 457.
The original NCIS cast (from left): Sasha Alexander, Michael Weatherly, Marc Harmon, Pauley Perrette and David Mccallum 
Domestic spinoff series: 5 (NCIS: Los Angeles, NCIS: New Orleans, NCIS: Hawaii, NCIS: Origins and NCIS: Tony & Ziva).
International spinoff series: 1 (NCIS: Sydney, which premiered in 2023).
International markets that license NCIS: More than 200.
Total episodes of NCIS: Los Angeles: 323, between 2009-23.
Guest stars who also appeared with Harmon in the 1987 comedy Summer School: 2 (Robin Thomas and Patrick Labyorteaux, who played lieutenant-turned-captain Bud Roberts).
First Ladies who have guested on the show: 1 (Michelle Obama appeared as herself toward the end of the Season 13 episode "Homefront” in 2016).
Guest stars who also were part of the main cast on Lost: 3 (Terry O’Quinn, Josh Holloway and Emilie de Ravin).
Guest stars who went on to be nominated for an Oscar: 2 (Abigail Breslin in 2004 and Jesse Plemons in 2006).
Jamie Lee Curtis guest starred on NCIS
Guest stars who went on to win an Oscar: 1 (Jamie Lee Curtis, who played Dr. Samantha Ryan across five episodes in Season 9).
Consecutive years that NCIS was the highest-rated broadcast TV series: 5 (it was dethroned by Tracker in the 2023-24 season).
Viewership in the 2023-24 season: 9.7 million.
Viewership in the 2024-25 season: 7.85 million.
Portraits of bad guys seen on the NCIS Most Wanted Wall: 15.
Number of real NCIS showrunners who have appeared on the wall: 1 (Bellisario!).
