For years, fans of NCIS have speculated about what it was really like working alongside Mark Harmon, who played the iconic Leroy Jethro Gibbs for nearly two decades. Now, several cast members are finally speaking out — and their comments confirm much of what viewers suspected about Harmon’s presence both on and off the screen. While Harmon has often been described as reserved, his colleagues are shedding new light on just how influential his behavior was behind the scenes.

According to insiders, Harmon carried himself with the same quiet authority as his on-screen counterpart, setting a professional yet supportive tone on set. Co-stars revealed that he wasn’t the loudest or most outgoing presence, but rather someone who led by example. “Mark always showed up prepared, focused, and ready to work,” one cast member shared, noting that his discipline helped shape the work ethic of the entire cast and crew.

At the same time, Harmon’s more private nature made him somewhat of a mystery even to those who worked closely with him. Castmates admitted that while he was deeply respected, he wasn’t one to engage in flashy antics or overshare his personal life. Still, his steady demeanor created a sense of stability during the show’s long run, something many attribute to NCIS’s enduring success.

In the end, what fans suspected appears to be true — Harmon wasn’t just Gibbs on screen; he embodied many of the same traits off camera. Quiet, commanding, and respected, his influence continues to be felt on NCIS, even after his departure from the main cast.