NCIS Leroy Gibbs character was based on creative imagination and various human models

If you’ve watched more than a few episodes of NCIS, you know Gibbs isn't just some TV character. He feels like an institution. Between the gut instincts, the strict rules, and those famous head slaps, it’s hard not to wonder if there’s a real-life super-agent out there who actually acts like that.

I always wondered about it.

So, is there a real Gibbs walking around? Not exactly. But the real story is actually better than a simple "yes" or "no." Gibbs turns out to be a clever mix of family history, the writer's imagination, and the actual personality of the man who played him, Mark Harmon.

Show creator Donald P. Bellisario confirmed years ago that the agent himself is fictional. But he didn't just pull that name out of thin air. It’s actually a pretty touching tribute to Bellisario’s own family. He named the character after his father, Leroy, and his grandfather, Jethro. So while the agent might be made up, the name carries a lot of weight.

And honestly, you can’t separate Gibbs from Mark Harmon. The guy on the page was just a blueprint at first; Harmon decided how Gibbs would actually feel to the audience. One of the executive producers pointed out that Gibbs’s quiet strength came right from the actor himself. Harmon has this unique way of controlling a room without ever raising his voice, and the writers really leaned into that. If Gibbs feels intense but totally calm, that’s not just the script—that’s the actor.

Then there’s the boat in the basement. That wasn't just some random quirk the writers threw in. Harmon actually worked as a carpenter before his acting career took off. Since he knew how to handle wood and tools in real life, they wrote it into the story. It adds a layer of authenticity you just can’t fake. When you see Gibbs sanding down that wood, the guy actually knows what he's doing.

Of course, the show uses real NCIS agents as consultants to make sure the police procedure is accurate. But the actual soul of the character? That’s a cocktail of Bellisario’s imagination mixed with Mark Harmon’s real-life skills.

That mix is probably why Gibbs resonates with people so much. He’s a fictional guy, but he’s built on a very real foundation. I love knowing that.