The following contains spoilers for NCIS Season 23, Episode 4, “Gone Girls,” which aired on Tuesday, November 4, on CBS. Created over Mark Harmon’s nearly two decades on NCIS and continued by Austin ...

Throughout his run in the "NCIS" franchise, Special Agent Leroy Jethro Gibbs (Mark Harmon) has followed a code — a set of rules, if you will. These self-imposed edicts inform both his personal and ...

Mark Harmon's Gibbs is such an iconic NCIS character, and his list of rules cemented him as one of the best. Although Harmon's Gibbs left NCIS in season 19, he remains a vital character to the show.