Behind-the-Scenes ‘Drama’ Is Brewing at ‘NCIS’ After Star Mark Harmon’s Son Ousted From Young Gibbs Role

Longtime NCIS star Mark Harmon’s son Sean Harmon is not reprising his role as young Jethro Gibbs in the new prequel, and the decision led to “some drama brewing behind-the-scenes” of the show, a source exclusively tells In Touch.

“Mark Harmon explained that his son Sean would stay on as an executive producer on the series but was no longer going to star as young Gibbs,” the insider explains.

Mark, 73, played special agent Jethro Gibbs on NCIS for 18 years before leaving the franchise as a series regular in 2021. The California native returned to narrate the new prequel, NCIS: Origins, which follows a young Gibbs at Camp Pendleton in 1991 shortly after the murder of his wife and child. Although Mark’s son Sean, 36, played a young Jethro Gibbs in flashback scenes across seven episodes of NCIS from 2008 to 2020 and assisted in taking the idea to showrunners, the Freaky Friday actor cited that Sean wasn’t asked to return for the prequel “mainly because he has a lot on his plate,” according to a source.

However, the insider says that “others are saying differently” in regards to the role change, with the “buzz on the set” being that CBS “wanted a bigger star to play Gibbs.” The show, which premiered on Monday, October 14, instead cast Secret Life of the American Teenager alum Austin Stowell for the “coveted” role of young Jethro Gibbs.

“And Mark actually agreed,” the source dishes. “Growing the franchise is the bottom line and nothing against Sean, but Austin has the leading man good looks and star power that the producers wanted.”

Mark opened up about returning to narrate the franchise spinoff, telling fans he’s made himself “completely available” on set for any questions the cast had. The actor told Variety that he had “full trust” in the cast and team behind it and “wasn’t hesitant’ to reenter the NCIS world.

“[Showrunners] David J. North and Gina Lucita Monreal had asked me to do the voiceover, and that was always part of my understanding. I don’t know if it was clear initially, how that was going to take place,” he explained ahead of the premiere on October 11. “Then the question was, after that, how are you going to do that? Is he standing there with his finger on his chin? Is he writing a book?”

Meanwhile, Austin, 39, was committed to getting the role of young Gibbs just right, telling People that he was single but “in a relationship” with the cast and crew of NCIS: Origins.

“I am here Monday through Friday … Remember those 300 people that I was telling you about? They are all my boyfriends and girlfriends,” he told the outlet on October 14. He also echoed Mark’s statements about his availability to mentor and said the longtime TV veteran was easy to work with.

“He always starts off his conversations with, ‘Do you need anything?’ That is so disarming,” the actor explained. “The guy is a global superstar. He could make it very uncomfortable for people to be around him. Certainly. I mean, for me, a guy who is stepping into the shoes of the character that he created and has become beloved and for everybody else that’s around here. That goes for the crew. He treats everyone with such respect.”