Mark Harmon, who portrayed Leroy Jethro Gibbs on NCIS for nearly two decades, has long been regarded as the show’s cornerstone. His departure in 2021 marked the end of an era, but his influence continues to resonate among the cast and crew.​

Co-stars have consistently praised Harmon’s professionalism and leadership. David McCallum, who played Dr. Donald “Ducky” Mallard, credited Harmon with bringing order to the show’s early chaotic production. Michael Weatherly, known for his role as Anthony DiNozzo, described Harmon as “a very rare person in this business”—straightforward, approachable, and devoid of celebrity pretense Looper.​

However, not all experiences were positive. Pauley Perrette, who portrayed Abby Sciuto, alleged that Harmon created a toxic work environment, citing an incident where his dog bit a crew member. She claimed that after the dog was allowed back on set, she felt unsafe, leading to her departure from the show .​

Despite these conflicting accounts, it’s evident that Mark Harmon’s impact on NCIS is profound and multifaceted. While many colleagues commend his mentorship and dedication, others highlight challenges that affected their experiences on set.