Tensions between Pauley Perrette and Mark Harmon on the NCIS set stemmed from an incident where Harmon’s dog bit a crew member. Despite objections, Harmon continued to bring the dog, creating a toxic environment.

Their disputes continued even after Perrette left the show in 2018. She became difficult to work with, refusing scenes and table reads with Harmon. The situation deteriorated to the point that they stopped sharing scenes.

Perrette took her frustrations to Twitter, suggesting a smear campaign against her. She hinted at physical assault allegations.

Ultimately, this conflict led her to retire from acting in 2020. She has consistently stated she will never work with Mark Harmon again.