First things first. Hide the women and children. (Season 7, Episode 23)

Rule #44

Clean up your own mess. (Season 7, Episode 24)

Rule #45

Never leave behind loose ends. (Season 3, Episode 24)

Rule #45

Sometimes you're wrong. (Season 7, Episode 24, titled "Rule Fifty-One")

Rule #51

Never trust a woman who doesn't trust her man. (Season 9, Episode 7)

Rule #69

You do what you have to for family.

Unwritten Rule

Pride: Laissez les bon temps rouler.
Gibbs: Let the good times roll.

Gibbs: How's your love life, DiNozzo?
Tony: Huh?
Gibbs: You still seeing the secretary?
McGee: He means Andrea.
Bishop: Andrea. Hmm. Who's Andrea?
Tony: Andrea. Oh yeah. Yeah. She's uh, I mean, it's kind of on an as-needed basis.
Pride: Friends with benefits?
Gibbs: Yeah well those aren't benefits like dental insurance.

Welcome aboard, probie.

Gibbs: What are SecNav's orders?
Vance: Now that we have Parsa - press him for intel. Enough to disable his entire terrorist network.
Gibbs: How hard?
Vance: Whatever it takes.

Rule number eleven. When the job is done, walk away.

Gibbs: (as he and Quinn look at the Vietnam Memorial Wall) No matter how many times I come here, it still gets to me. You look at a name, and you have to look at a reflection of yourself. You are among the fallen.
Quinn: Yeah. Difference is, you can leave. The names don't.

NCIS Quotes

Bishop: Seriously? How'd you get that?
Tony: Well, it's like Gorillas in the Midst. You'll get to understand his grunts.

Torres: When I break out the glass, maybe I can rip out the bars.
Bishop: With what? Your superhuman strength?