Mark Harmon has been the face of NCIS as Special Agent In Charge Leroy Jethro Gibbs since its inception in 2003, but why did Mark Harmon leave NCIS in season 19? While Harmon continued to serve as an Executive Producer despite Gibbs’ absence from the show, his character remained out of the picture. NCIS is CBS’ longest-running scripted primetime series, following the lives and adventures of the federal special agents responsible for investigating felony military crimes, preventing terrorism, and protecting secrets for the Navy and Marine Corps.
