Mark Harmon will appear as the elder version of Leroy Jethro Gibbs in all episodes of the upcoming third season of NCIS: Origins. The announcement comes as the prequel series prepares to resume this fall on CBS.
Harmon, who executive produces and narrates the series, will feature on screen alongside a present-day mystery connected to Gibbs's time at Camp Pendleton in the 1990s. He previously portrayed the character for more than 18 seasons on the original NCIS before departing in season 19.
Austin Stowell continues in the role of a younger Gibbs. Harmon had made limited appearances as the elder character in the series premiere and a November 2025 crossover episode with NCIS.
The second season concluded with a kiss between Gibbs and Lala, played by Mariel Molino, and the kidnapping of Randy after he discovered sensitive information. Additional executive producers for season 3 include David J. North, Sean Harmon, Michele Greco, and Eric Christian Olsen.
The military procedural is scheduled to air Tuesdays at 10/9 on CBS and stream on Paramount+.