The REAL Reason Mark Harmon Left NCIS—And The Shocking 2025 Comeback

The departure of Mark Harmon from *NCIS* in 2021 sent shockwaves through the television landscape, leaving a massive, Gibbs-sized hole in the long-running CBS procedural. For nearly two decades, Harmon’s portrayal of the stoic, rule-bending Supervisory Special Agent Leroy Jethro Gibbs was the undisputed anchor of the Naval Criminal Investigative Service team, making his exit in Season 19 one of the most significant cast changes in modern TV history. Fans immediately began searching for the "real" reason he walked away from the show that defined his career.

As of December 2025, the narrative surrounding his exit has become much clearer, evolving from speculation about health and contract disputes to a definitive, character-driven conclusion. The most crucial and recent update, however, is not *why* he left, but the shocking confirmation that the 74-year-old actor is officially returning to the *NCIS* universe, reprising his iconic role for a major crossover event and taking on a new executive producer role in the franchise's future.

Mark Harmon: A Legendary Career Profile

Thomas Mark Harmon is more than just Agent Gibbs; he is a Hollywood veteran whose career spans five decades, transitioning from a college football star to one of television's most recognizable faces.

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• Full Name: Thomas Mark Harmon
• Born: September 2, 1951, in Burbank, California
• Age (as of 2025): 74 years old
• Parents: Tom Harmon (Heisman Trophy winner and football legend) and Elyse Knox (actress and fashion designer)
• Spouse: Pam Dawber (married since 1987)
• Early Career Highlights: Before *NCIS*, Harmon was a college quarterback for the UCLA Bruins. His major acting breakthroughs included playing Dr. Robert Caldwell on *St. Elsewhere* and a memorable, Emmy-nominated guest role as Secret Service Agent Simon Donovan on *The West Wing*. He also starred in *Chicago Hope* and the film *The Presidio*.
• NCIS Tenure: Portrayed Leroy Jethro Gibbs from 2003 to 2021, appearing in 435 episodes.
• Current Status: Executive Producer and returning actor in the *NCIS* franchise.

The True, Character-Driven Reason for Gibbs' Exit

The speculation surrounding Mark Harmon's departure was intense. Rumors ranged from long-term health issues to a major contract dispute with CBS. While the grueling schedule of a procedural drama was certainly a factor for an actor his age, the official and most consistent explanation centers entirely on the natural conclusion of the Leroy Jethro Gibbs character arc.

Finding Peace in Alaska: The Story Arc Conclusion

Gibbs' final appearance as a series regular came in Season 19, Episode 4, titled "Great Wide Open." After surviving a near-fatal boat explosion and a subsequent investigation, Gibbs decides not to return to the Naval Criminal Investigative Service.

He chooses to remain in the tranquil environment of Naktok, Alaska, where he had been tracking a contract killer.

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The character's final, emotional conversation with his protégé, Special Agent Timothy McGee (played by Sean Murray), confirmed the decision. Gibbs states, "I'm not going back, Tim. I'm not going back home."

Mark Harmon himself later clarified his rationale, emphasizing that the story had simply run its course. He stated that the character had reached a point of contentment and peace that made a return to the high-stakes, stressful environment of the Washington D.C. headquarters unnecessary.

Showrunner Steven D. Binder supported this, explaining that Gibbs had been through so much trauma—the death of his wife and daughter, multiple near-death experiences—that giving him a peaceful, satisfying exit was the right creative choice for the series. The door was intentionally left open, however, with Binder stating at the time, "Regarding the future of Gibbs, as long-time fans of the show know, never count Leroy Jethro Gibbs out."

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The Contract and Creative Control Factors

While the story arc is the official reason, behind-the-scenes factors played a role in the timing of the exit:

• Reduced Role: Reports indicated that Harmon was ready to leave after Season 18. To keep the show from being canceled—as CBS was reportedly ready to end it without him—Harmon agreed to return for a limited number of episodes in Season 19 to ensure the longevity of the series and the jobs of the cast and crew, including Sean Murray, Wilmer Valderrama (Nicholas Torres), and Diona Reasonover (Kasie Hines).
• Executive Producer Role: Harmon remained an Executive Producer after his on-screen departure, maintaining creative influence over the show. This allowed him to step back from the demanding 12-to-15-hour-a-day acting schedule while still contributing to the *NCIS* universe.
• Creative Differences: While not a major conflict, the desire for a less demanding schedule and a final, meaningful conclusion for Gibbs was a form of creative difference that was ultimately resolved by crafting the Alaska storyline.

The Shocking 2025 Return and the Future of the NCIS Franchise

The most compelling and up-to-date information is that Mark Harmon’s time as Leroy Jethro Gibbs is definitively not over. His planned "retirement" from the screen has been short-lived, with a major Hollywood comeback now underway.

Gibbs Reprises His Role in NCIS: Origins Crossover

In a major announcement, CBS confirmed that Mark Harmon will return to the *NCIS* universe in 2025. This return is set to be a special guest appearance during a significant crossover event with the new prequel series, *NCIS: Origins*.

*NCIS: Origins* explores the early life and career of Gibbs, with the younger version of the character being played by actor Austin Stowell. The crossover event is highly anticipated, as it will bridge the past and present of the Naval Criminal Investigative Service timeline.

Executive Producer of NCIS: Origins

Harmon is not just acting; he is a driving force behind the new prequel. He is serving as an Executive Producer on *NCIS: Origins*, a role that ensures the integrity of the Gibbs character and the franchise's continuity.

This new role allows him to remain deeply involved with the *NCIS* franchise—a massive topical authority entity for CBS—without the intense physical demands of leading a weekly procedural. This move also confirms the show’s enduring success, which has spawned multiple successful spin-offs like *NCIS: Los Angeles*, *NCIS: New Orleans*, and *NCIS: Hawai’i*.

A Broader Hollywood Comeback

Beyond the *NCIS* world, Harmon is reportedly plotting a broader return to acting. After initially enjoying his downtime, sources close to the actor suggested he missed the "buzz" of being on set.

This desire to "stretch himself" has led to him being spotted on the set of other projects, most notably a role in the upcoming sequel *Freaky Friday 2*, confirming his intention to move beyond the Gibbs persona and explore new acting challenges after nearly two decades in the same role.

Ultimately, Mark Harmon left *NCIS* because the compelling story of Leroy Jethro Gibbs had reached a natural, peaceful conclusion in the Alaskan wilderness. However, thanks to the show's enduring popularity and his continued role as an Executive Producer, his "retirement" was never truly a permanent farewell. His confirmed return in 2025 ensures that the legacy of Gibbs will continue to shape the *NCIS* universe for years to come.