Mark Harmon’s Feud With NCIS Creator Donald P. Bellisario, Explained

“NCIS” creator Donald P. Bellisario once threatened to cancel the series over a casting decision, proving that he wielded some major influence over the folks at CBS back in the day. However, some rumors out there indicate that Mark Harmon, who played Leroy Jethro Gibbs on the show, had more clout than the acclaimed showrunner — and he used it to get him fired. In reality, though, the story isn’t as simple as that.

According to the scuttlebutt, Harmon and Bellisario’s feud stemmed from the Gibbs star being unhappy with the former “NCIS” showrunner over the behind-the-scenes working conditions. The cast and crew had to work long days, and Harmon reportedly felt that there was too much disorganization and chaos on the set. Bellisario parted ways with “NCIS” after four seasons shortly after, leading to the belief that CBS fired him from his own series at the behest of Harmon.

As is often the case with drama of this ilk, however, this was somewhat overblown by the media, although there is also some truth to the story. Keeping that in mind, let’s find out what went down from the perspectives of people who actually worked on the show at the time.

There is some truth to the story about Mark Harmon having issues with the working conditions on “NCIS” during Donald P. Bellisario’s run. In an oral history published by The Hollywood Reporter in 2023, executive producer Charles Floyd Johnson recalled the actors struggling to learn their lines, as they had no idea what their characters’ storyline arcs were for each episode. This led to Harmon speaking up about the situation, but he never intended for anyone to lose their job. Per Johnson:

“Harmon just felt like it was too hard. He never said to anybody, ‘Get rid of Don.’ He just said, ‘This is too hard to work this way.’ Eventually, the network went to Bellisario and said, ‘Maybe you should work from a distance from it and not be quite as involved in terms of the way you work.’ And so Bellisario, by the fifth year, was gone.”

Johnson also noted that he had to act as a middle man between Bellisario and Harmon, as there was some tension between the pair on the set, which suggests their feud was legit. As for the reported firing, Bellisario told THR that he left the series on his own accord because wanted to focus his time and energy on other things. Unfortunately, that wasn’t the end of the drama between him and CBS, especially when the “NCIS” franchise started to expand.

The “NCIS” property has produced a variety of spin-offs, most of which haven’t caused any serious controversy. However, the first of the bunch, “NCIS: Los Angeles,” was at the center of a lawsuit from Donald P. Bellisario, who sued CBS for not tapping him to make the project.

In short, Bellisario had a clause in his CBS contract that gave him the first option to make an “NCIS” spin-off. Problem was, his departure from the main series resulted in the network hiring other creators for “NCIS: Los Angeles,” so Bellisario wanted compensation. The lawsuit was ultimately settled out of court, with CBS claiming that the agreement was amicable, while emphasizing that the network still thought highly of the “NCIS” creator.

“NCIS: Los Angeles” ended after 14 seasons, making it one of the most successful shows in the entire franchise. Bellisario was probably paid handsomely following the lawsuit, but it’s still unknown if he and Mark Harmon ever reconciled in the wake of their on-set spats all those years ago.