Why Mark Harmon Almost Quit NCIS A Lot Earlier

After nearly two decades playing Supervisory Special Agent Leroy Jethro Gibbs on “NCIS,” Mark Harmon had his final episode in Season 19’s Episode 4 in October 2021. He still has a limited-episode deal and will continue to work on the show in an off-screen capacity, but Harmon actually could have left
the show a lot earlier.
During Season 4, CBS was forced to choose between Harmon and Donald Bellisario, the show’s creator and original showrunner. A source described Bellisario’s management style as “chaotic” with him sending scripts to the cast last-minute and making them work 16-hour days. It was negatively affecting Harmon’s life, and in the end, CBS chose the actor over Bellisario.
David McCallum, who plays Dr. Donald “Ducky” Mallard more or less confirmed these reports during a 2014 interview. Bellisario, however, accused Harmon of being difficult to work with, saying that he had asked the actor to reshoot a scene and Harmon redid it in the same way and never spoke to him again.