Mark Harmon’s Son Sean Explains Why He’s Not Playing Young Gibbs in ‘NCIS’ Prequel

Sean Harmon played young Gibbs on 'NCIS' and came up with the idea of 'NCIS: Origins.' But he won't portray Gibbs on the new show.

When NCIS needed someone to portray a young Leroy Jethro Gibbs, the show’s team didn’t need to look far to find the right person.

Sean Harmon – the son of Gibbs actor Mark Harmon – stepped into the role as the youthful NCIS agent for seven episodes between 2008 and 2020. But when it came time to cast someone to play young Gibbs in the new prequel series NCIS: Origins, producers went in a different direction.

Sean Harmon didn’t intend to ‘make a career out of’ playing Gibbs

The idea of an NCIS spinoff focused on young Gibbs originated with Sean, who came up with the concept while playing the character in a 2020 episode. NCIS: Origins will explore Gibbs’ early days with the Naval Criminal Investigative Service, when he is still reeling from the murder of his wife and young daughter.

“It was a lightning-bolt moment. Gibbs is a guy who has something broken inside, a guy who at one point could have down a darker path,” Sean said 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,” he added. “But on NCIS: Origins, this is a guy with none of the answers and all the trauma.”

Both Sean and his dad will serve as executive producers on NCIS: Origins. The elder Harmon will also act as the show’s narrator. But Sean Harmon won’t appear on screen in the new series. He’s fine with that.

“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 happy to see another person’s take on the character he played for 19 seasons. (Harmon left NCIS in 2021.)

“I’m fine with the stepback role and (to) let the (new) cast do the work,” Harmon said. “I’m pleased to be part of it. I’m a distant part. I’m just here to support.”

That support included some words of advice for Austin Stowell, who has been cast as Gibbs in NCIS: Origins and is putting his own stamp on the iconic character.

“It’s not the Gibbs the world knows. This is someone broken, searching for his identity,” Stowell said. “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 moves to its regular 10 p.m. timeslot starting Oct. 21.

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