Though it’s impossible to replace Harmon’s legendary version of the character, NCIS: Origins adds new weight to his story by fleshing out his past. True to its title, the spinoff, launched in 2024, reveals the origins of some of Gibbs’ most essential stories and characteristics from the flagship. The series also delves into the backgrounds of other NIS employees and their key experiences, such as Dick Kowalski (Michael Harney) and Mary Jo (Tyla Abercrumbie). However, Gibbs remains at the heart of the story’s unfolding.
How Mark Harmon And Austin Stowell’s Character Established Gibbs’ Rules, Explained
Gibbs’ list of rules is as old as the series itself. The Special Agent-in-Charge first established his code of conduct in NCIS Season 1, Episode 1, “Yankee White,” the iconic premiere of the show, which aired in 2003 after its backdoor pilot on JAG. In the premiere, Gibbs established three rules when introducing Kate Todd (Sasha Alexander) to the NCIS investigation process. One, never let suspects stay together. Two, always wear gloves at a crime scene. And three, don’t believe what you’re told. Double check.
Furthermore, flashbacks in NCIS established what inspired Gibbs’ code. A look into the past of Mark Harmon’s Gibbs character, played by Sean Harmon in NCIS, reveals that the younger Shannon (Aviva Baumann) inspired Gibbs to create a personal code. She told him that “everyone needs a code they can live by,” saying that one of her own personal boundaries was “never date a lumberjack.” The encounter inspired Gibbs to write his own guidelines on scraps of paper, like napkins and envelopes, which he would later share with his team.
NCIS: Origins added a vital piece of the story about Gibbs’ rules in Season 1, Episode 3, “Bend, Don’t Break.” Gibbs is visiting the home he shared with Shannon and Kelly in the installment, and, having trouble moving on, decides to throw away his box of rules. An older Gibbs says that he lost his family even though he followed them, reminiscing about why he had cast them aside. However, NCIS: Origins reveals that Gibbs’ dad, Jackson Gibbs (Robert Taylor), rescued them from the trash and returned them, knowing his son needed something to hold onto.
Gibbs’ Most Important Rule Is Rule #9: Never Go Anywhere Without A Knife
In total, Gibbs has revealed about 40 of his rules on NCIS. However, considering the rules are numbered into the 90s, his personal code of conduct could have 100 entries or more. Still, the most crucial rule is number nine, “never go anywhere without a knife.” The rule is introduced in NCIS Season 1, Episode 13, “One Shot, One Kill.” Both the rule and the episode evoked Leroy’s days in the Marine Corps as a Gunnery Sergeant, as Gibbs puts his uniform back on to lure and catch self-taught sniper Kyle Hendricks (Noah Segan).
In a literal sense, carrying a knife can be absolutely vital, since it’s all that a trained technician would need to survive on their own in the wilderness. However, the rule extends beyond the literal aspect of a knife and symbolizes the importance of always being prepared for any situation. The rule is so critical that it’s repeated in NCIS Season 17, “In the Wind,” which features Ziva David after her exit, and Season 6, “Life Before His Eyes,” a reflective episode for Gibbs that revisits some of his most formative experiences.
NCIS Season 23 Episode 4 Emphasizes The Importance Of Gibbs’ Rule #9
Garnered from her experience as a Marine Raider, Molly’s resourcefulness is key to the operation, and no one would understand that more than Leroy Jethro Gibbs. While “Gone Girls” didn’t nod to Gibbs directly, the series called back to Gibbs’ rules overtly in NCIS Season 23’s two-part premiere. Alden Parker (Gary Cole) left a clue, the number 51, for his team. It is tied to Gibbs’ rule, “Sometimes — you’re wrong.” It was a vital message to Parker’s team that he was still alive, proving that Harmon’s character and Gibbs’ rules also live on in the original series.

