For nearly two decades, NCIS fans were drawn to the steady presence of Special Agent Leroy Jethro Gibbs, brought to life by Mark Harmon. When rumors of Harmon’s departure began circulating around Season 19, the reaction was immediate and emotional—both from viewers and from those who had worked alongside him for years. As Gibbs stepped away, his co-stars reflected on the lasting influence Harmon had on the series, the cast, and the culture behind the scenes.
David McCallum (Dr. Donald “Ducky” Mallard)
The late David McCallum often spoke candidly about the show’s early growing pains. He credited Harmon with providing structure and stability during uncertain beginnings.
“There was always some degree of confusion,” McCallum once said. “But it’s all gone now. Mark was instrumental in getting our home in order. I sincerely thank him for that.”
For McCallum, Harmon wasn’t just a leading man—he was a grounding force.
Michael Weatherly (Anthony DiNozzo)
Michael Weatherly described Harmon as a rare presence in Hollywood: approachable, calm, and free of ego. He praised Harmon’s leadership style, calling him “a straightforward, assertive guy” who never hid behind celebrity status.
Weatherly has also acknowledged Harmon’s influence on his own career, particularly as he transitioned into a lead role on Bull, noting that lessons learned on NCIS stayed with him.
Cote de Pablo (Ziva David)
For Cote de Pablo, Harmon represented mentorship and consistency. She has highlighted his commitment to excellence and his willingness to challenge creative boundaries.
De Pablo often referred to Harmon as both a mentor and a father figure—someone who supported her growth not only as an actress, but as a person navigating a demanding industry.
Sean Murray (Timothy McGee)
Sean Murray has repeatedly credited Harmon as the foundation of NCIS’s longevity.
“We wouldn’t be here 16 years later if it wasn’t for Mark Harmon,” Murray said.
Having worked with Harmon years earlier on Hearts of the West, Murray recalled being struck by his professionalism, discipline, and respect for the craft—qualities that carried over into NCIS.
Pam Dawber (Marcie Warren)
Pam Dawber, Harmon’s wife and a guest star on the series, offered a deeply personal perspective. She described him as selfless and motivated by harmony rather than ego.
According to Dawber, Harmon’s leadership came from a desire to see everyone succeed, creating a balanced and supportive environment for the ensemble cast.
Brian Dietzen (Dr. Jimmy Palmer)
Brian Dietzen spoke about how Harmon’s recognition of his work helped elevate the character of Jimmy Palmer from a supporting role to a fan favorite.
Dietzen praised Harmon’s mentorship and credited him with fostering a collaborative atmosphere where storytelling could evolve organically.
Wilmer Valderrama (Nick Torres)
Wilmer Valderrama described Harmon as a source of positivity and steady leadership. He highlighted the genuine camaraderie among the cast, joking about their close bond while emphasizing that Harmon led with respect, kindness, and quiet authority.
Mark Harmon’s portrayal of Leroy Jethro Gibbs was defined by restraint, depth, and authenticity—qualities that mirrored his presence off-screen. His warmth, humility, and unwavering professionalism shaped the culture of NCIS, leaving a lasting impression on everyone involved.
Through the words of his co-stars, one truth becomes clear: Mark Harmon didn’t just anchor a television series—he built a legacy of leadership, trust, and excellence that will remain inseparable from NCIS for years to come.