What Happened To Gibbs Star Mark Harmon After His NCIS Exit?

In the 21 years since the series began, plenty of actors have left "NCIS." However, for its first 18 seasons, Mark Harmon steadfastly filled his role as the show's longtime lead, Supervisory Special Agent Leroy Jethro Gibbs. His commitment to the series resulted in many coming to view Harmon as the face of "NCIS," but that didn't stop him from eventually stepping away from the show in 2021. Indeed, Harmon made his long-dreaded exit as Gibbs during "NCIS" Season 19, and the series has been forced to try to make up for his absence ever since.

For his part, Harmon has kept relatively busy in the years since he left his full-time responsibilities to "NCIS" behind. He hasn't appeared in any new movies or TV shows since making his last screen appearance on "NCIS," but he did publish his first book in November 2023. Harmon co-wrote the book, titled "Ghosts of Honolulu: A Japanese Spy, A Japanese American Spy Hunter, and the Untold Story of Pearl Harbor," with longtime "NCIS" technical advisor Leon Carroll Jr.. The book explores the conflict that slowly but surely escalated between Japanese and U.S. military intelligence agents in the period leading up to the 1941 attack on Pearl Harbor and America's entry into World War II.

The non-fiction book gives Harmon and Carroll Jr. the chance to shine a light on the history of the Office of Naval Intelligence (ONI), which established the Naval Investigative Service (NIS) after the conclusion of WWII. The NIS eventually transformed into the Naval Criminal Investigative Service (NCIS), aka the organization that inspired the TV series Harmon worked on for nearly 20 years.

By writing "Ghosts of Honolulu," Mark Harmon found a way to honor both the NCIS and its agents. "On the show, we used to use the fact that no one knew who this agency was or what they did as a point of humor, but for those doing this difficult job for real, there was nothing funny about it," he told PEOPLE in June 2023. "To provide these men and women a chance to tell their story, their REAL story, has been both fun and educational for me."

While he hasn't appeared in anything, including any episodes of "NCIS," since he left the CBS series, it's worth noting that Harmon is set to return to the "NCIS" universe. However, he will not be back in the form many may have expected. It was revealed in January that Harmon will executive produce and narrate "NCIS: Origins," a new TV series that follows a younger version of his "NCIS" character, Leroy Gibbs, as he works to establish himself as an investigative agent in the early 1990s. 

The "NCIS" prequel is slated to premiere on CBS during the 2024-25 broadcast TV season. According to Deadline, the show was originally conceived by Harmon and his son, Sean, who has previously played a younger version of Gibbs in several episodes of "NCIS."

An actor has not yet been hired to portray the role on "NCIS: Origins." That said, most fans will likely agree that whoever is cast will have big shoes to fill, and that fact will be made even more apparent by Harmon's presence as the prequel series' narrator.