For nearly two decades, Mark Harmon was the heart of NCIS, playing Special Agent Leroy Jethro Gibbs. Cast members have opened up about his impact both on-screen and behind the scenes. Harmon was praised as a consummate professional and a natural leader. One cast member shared, “Mark set the tone for the show,” highlighting his preparedness, support, and ability to make everyone feel valued. Despite his reserved nature, Harmon’s kindness and mentorship, especially to younger cast members like Emily Wickersham, were widely recognized. His legacy, built on camaraderie, respect, and excellence, continues to shape NCIS as the show moves forward without him, deepening fans’ admiration for him both as an actor and a person.