Five years after stepping away from the flagship NCIS, Mark Harmon is coming back to the franchise as Leroy Jethro Gibbs in NCIS: Origins. CBS says he will appear in every episode of season 3, due in fall 2026, as the series splits its story between a younger Gibbs played by Austin Stowell and the present-day version Harmon voices and produces.
Five years after stepping away from the flagship show, Mark Harmon is slipping back into Leroy Jethro Gibbs’ shoes, but his home base has changed. CBS has confirmed he will be present in every episode of NCIS: Origins season 3, while staying off the main NCIS roster. The new run leans into a two-timeline setup, pairing Austin Stowell’s younger Gibbs with Harmon’s present-day version as the story heads toward its fall 2026 debut.
Mark Harmon is stepping back into the NCIS universe
For years, the absence has been felt in small ways, a familiar voice here, a brief moment there. Now the news lands with more weight: Mark Harmon is returning to the NCIS franchise as Leroy Jethro Gibbs. The surprise is in the shape of it. This is not a walk back into the flagship series, but a deeper turn into its prequel orbit.
CBS has confirmed Harmon will appear on screen throughout NCIS: Origins season 3, a much bigger commitment than the limited involvement he’s had recently. For longtime viewers, it reads less like a cameo strategy and more like a decision to make Gibbs central again, just on a different stage.
Gibbs in 2 timelines, one case that won’t stay buried
The new season is built around 2 eras running side by side. One track stays in the early 1990s at Camp Pendleton, following Gibbs in his formative period as a developing investigator. The other moves in the present day, where Harmon’s Gibbs is pulled into a serious case with consequences that reach far beyond a quiet town.
That structure lets the series do something the original rarely attempted: show cause and effect across decades, rather than only referencing backstory in passing. And it clears space for Austin Stowell to play the younger Gibbs while Harmon embodies the version audiences already know, with the two performances designed to echo each other.
the story he never told enters a new chapter… Mark Harmon will return to NCIS: Origins as Gibbs for all episodes of Season 3. 👏👏 #NCISOrigins #NCIS #MarkHarmon #Gibbs
♬ original sound – The NCISverse – The NCISverse
More than a role, Harmon’s steady hand behind the camera
Harmon’s presence is not limited to acting. He remains attached as narrator and executive producer, keeping a guiding hand on the tone and the way Gibbs is framed. This is the case even as the show expands its mythology, using the prequel format to slow down and examine how professional habits become personal rules.
According to the show’s setup, season 3 grows out of a crossover that took place during season 2, tied to a case involving the death of a Marine officer. The connective tissue matters here: what began as an event episode is now being treated as the spine of a full-season investigation.
A legacy that started in 2003, and keeps finding new angles
Gibbs first arrived in 2003 through JAG, a backdoor introduction that quickly turned into a phenomenon. Harmon then anchored the main series for 18 seasons before stepping away in 2021. For a character so defined by routine, the return feels fittingly procedural: the work is unfinished, so the story follows him back to it.
NCIS: Origins season 3 is expected to air on CBS in the fall, with specific scheduling details to be confirmed by the network. For viewers in the U.S., it’s a clear invitation: revisit Gibbs, but watch him from 2 directions at once.