It's impossible to talk Leroy Jethro Gibbs without mentioning Mark Harmon. The latter may not have been the first actor considered for the part of Gibbs, but he has definitely made it his own, and is a large part of why NCIS is still a successful franchise after two and a half decades.
NCIS shocked fans in all the right ways when it announced that it would be releasing a spin-off that would be focused on the early years of Gibbs titled Origins. The spin-off would be set during the early 1990s, roughly ten years before the events of the first NCIS season. The thing on everyone's mind, of course, is whether Harmon will return to reprise his signature role...
NCIS: Origins will cast a new actor as Gibbs
Well, yes and no. Harmon has been confirmed to be involved with NCIS: Origins as an executive producer, as he is with the regular NCIS, but the Deadline report that broke the news confirmed that a search is currently underway to find an actor who could believably play the young version of Gibbs.
This casting news means that NCIS will not be going the Hollywood blockbuster route, and de-aging Harmon with CGI so that he could convincingly play a younger version of the character he helped to establish. It's a trend that kicked off with Jeff Bridges in Tron: Legacy (2010), and has been used to an egregious level in franchises like The Avengers and Indiana Jones.
Sean Harmon, Mark's son, and the actor who played young Gibbs during select episodes of NCIS, will not be reprising his role either. Both men, who were instrumental in making the character so popular, will be working on NCIS: Origins behind the scenes. There is, however, a silver lining.
Mark Harmon will return to narrate the prequel series
Deadline confirmed that Mark Harmon will be narrating each episode of NCIS: Origins, which means he will technically be playing Gibbs in new stories, even if we only hear his voice. It's a structure that is somewhat similar to The Adventures of Young Indiana Jones (1992-96), in which actor George Hall narrated as the older version of the character.
Considering that the odds were slim that Harmon would return to NCIS in a full-time capacity, getting him to narrate prequel stories as a wet-behind-the-ears Gibbs is the next best thing! We can't wait for the show to premiere in 2025.