For nearly two decades, Mark Harmon’s portrayal of Special Agent Leroy Jethro Gibbs captivated NCIS fans with its depth, strength, and subtlety. But beyond his on-screen presence, Harmon’s off-screen leadership left a lasting impression on the cast and crew. As whispers of his potential exit in Season 19 surfaced, his co-stars reflected on the profound impact he had on the show’s success and their personal growth.

Veteran actor David McCallum credited Harmon with bringing order to the early, uncertain days of NCIS, while Michael Weatherly called him a rare and grounded force in Hollywood. Cote de Pablo described Harmon as both mentor and father figure, praising his constant push for creative excellence. Sean Murray, whose connection with Harmon began years earlier, said the show’s longevity was largely due to Harmon’s work ethic and commitment.

Other cast members echoed similar sentiments. Brian Dietzen praised Harmon’s collaborative spirit and mentorship, while Wilmer Valderrama emphasized the positivity and genuine connection Harmon fostered among the ensemble. Harmon’s wife, Pam Dawber, also highlighted his selfless nature and focus on the greater good, both on set and off.

Together, their reflections reveal a portrait of a man whose influence extended far beyond his role. Harmon not only shaped NCIS as a series but also nurtured a culture of respect, humility, and excellence—leaving an enduring legacy that continues to define the heart of the show.