Mark Harmon’s Son Sean Drops Bombshell: The Real Reason He Won’t Play Young Gibbs in ‘NCIS’ Prequel!

When NCIS needed an actor to portray a young Leroy Jethro Gibbs, the show didn’t have to look far. Sean Harmon, the son of Mark Harmon (who famously plays Gibbs), took on the role for seven episodes between 2008 and 2020. However, when it came time to cast a younger version of Gibbs for the new prequel series NCIS: Origins, the producers decided to go in a different direction.

Sean Harmon Didn’t Intend to Make a Career Out of Playing Gibbs

The concept for an NCIS spinoff centered on a young Gibbs was actually Sean Harmon’s idea. He developed the concept while playing the character in a 2020 episode. NCIS: Origins will dive into Gibbs’ early days with the Naval Criminal Investigative Service, focusing on a time when he is still dealing with the trauma of losing his wife and daughter.

“It was a lightning-bolt moment. Gibbs is a guy who has something broken inside, a guy who at one point could have gone down a darker path,” Sean shared during an appearance at the TCA Summer 2024 press tour (via USA Today). “On NCIS, Gibbs had 30 years to come to terms with the trauma. But on NCIS: Origins, this is a guy with none of the answers and all the trauma.”

Both Sean and Mark Harmon will serve as executive producers on NCIS: Origins, with Mark also narrating the series. Despite his deep involvement, Sean Harmon won’t be appearing on screen in the new show. He’s perfectly content with that decision.

“It was an absolute honor to step into the role; it will always be something I’ll hold close to my heart,” he said. “In truth, I never intended to make a career out of it.”

Mark Harmon is Happy to Be a ‘Distant’ Part of NCIS: Origins

As for Mark Harmon, he’s excited to see someone else’s interpretation of the character he portrayed for 19 seasons. (Harmon exited NCIS in 2021.)

“I’m fine with the step-back role and letting the new cast do the work,” Harmon remarked. “I’m pleased to be part of it. I’m a distant part. I’m just here to support.”

Mark’s support included some advice for Austin Stowell, who will portray the younger Gibbs in NCIS: Origins and is making the role his own.

“It’s not the Gibbs the world knows. This is someone broken, searching for his identity,” Stowell explained. “During the screen test, Mark came up to me and gave me two words that I’ll remember forever — ‘trust yourself.’”

NCIS: Origins premieres Monday, Oct. 14, at 9 p.m. ET on CBS. It will move to its regular 10 p.m. timeslot starting Oct. 21.