Leroy Jethro Gibbs is the special agent in charge on NCIS.

Gibbs joined the United States Marine Corps instead of attending college. He became a Scout Sniper.

In his free time, he is occasionally shown in his basement building a boat, which he named after his daughter.

Gibbs' age has never been revealed, but it was shown that he was born in rural Stillwater, Pennsylvania. His father, Jackson Gibbs, owns a store (the Stillwater General Store) in the same town.

It has been mentioned in the episode "Frame Up" that Gibbs' father was possibly in the United States Army Air Force because Gibbs refers to a pin-up on his father's P-51 Mustang.

He is named after his father's friend, Leroy Jethro, who was his business partner in the store after having worked together in the coal mines. The younger Gibbs left Stillwater in 1976 at the approximate age of 18-20 and, according to his own statements, did not return for over 30 years.

At NCIS, Gibbs is portrayed as a consummate organizer, disciplined and demanding. These traits often put him in a stand-off with other authorities when pressure is being asserted at his team.

He remains a Marine reservist.

Before the time in which NCIS is set, Gibbs travelled extensively on operations, particularly in Eastern Europe, demonstrated by many flashbacks, many including Director Jenny Shepard.

Gibbs displays a continuous urgency about the investigation he pursues, specifically when being given technical information about, complex subject matter.

The typical response to such information is "Give it to me in English", thus forcing the expert to get to the point, as well as making it easy on the audience.

Gibbs has been married three times and had one daughter named Kelly.

Leroy Jethro Gibbs Quotes

‘You think you’re alone in the dark. Close your eyes. Remember everything good.’ My mom said that to me just before she died. Smart lady.

Gibbs

Gibbs: It’s strictly voluntary.
McGee: I’m good.
Gibbs: Well, you got new responsibilities.
McGee: Boss, I appreciate that, but… don’t forget, I’m an NCIS Special Agent.

NCIS Quotes

[voiceover] Anyone can achieve their fullest potential, who we are might be predetermined, but the path we follow is always of our own choosing. We should never allow our fears or the expectations of others to set the frontiers of our destiny. Your destiny can't be changed but, it can be challenged. Every man is born as many men and dies as a single one.

McGee

McGee: All right. Well you should probably know that Abby and I used to date?
Bishop: Ew. Like, each other?
McGee: Yeah.
Bishop: Wait - isn't that a violation of rule 12, never date a....
McGee: It was a long time ago. After we'd broken up, one night I went to her lab. Found a scribbled piece paper; a list. Potential boyfriends had to fulfill certain conditions by a pre-arranged date or else, goodbye.
Bishop: Such as.
McGee: Things started off relatively normal: opening the door for her, flowers, putting the seat down. Then around number 8, it gets uh...
Bishop: What?
McGee: Does she know you have these?
Bishop: Does she know you have these?
McGee: Yeah she wasn't happy when she found out.
Bishop: These are all very specific.
McGee: Yeah.
Bishop: These ideas apply to you?
McGee: No those rules weren't in place when we were together. At least I don't think so.
Bishop: What's with the two month cutoff? Abby's sabotaging herself. I've seen stuff like this before. We have to talk to her.