Why Gibbs Lived by 91 Strict Rules on 'NCIS'—and Which Ones Mattered Most For nineteen seasons, Special Agent Leroy Jethro Gibbs led his NCIS team using a strict code of conduct. Played by Mark Harmon, the character frequently passed down his wisdom through a numbered list of rules. Gibbs had at least ninety-one rules in total, writing them down on napkins and scraps of paper over the years. The tradition actually started because of his wife, who believed everyone needed a code to live by. Some of his guidelines were highly practical for investigations, like Rule Number Two: always wear gloves at a crime scene. Rule Number Nine advised agents to never go anywhere without a kn*fe, serving as both a tool and a we*pon for self-defense. Other rules focused heavily on loyalty and teamwork. His very first rule was to never screw over a partner, while Rule Twenty-Eight reminded his team that asking for help is never a sign of weakness. Gibbs even tried to prevent office drama with Rule Twelve, which banned dating co-workers—a rule several agents struggled to follow throughout the show. But his final guideline might be the most famous. Rule Ninety-One simply stated that when you decide to walk away, you should never look back. Gibbs took this rule so seriously that he named his boat after it, eventually leaving his team behind to live a quiet life in Alaska. Harmon recently returned to the present-day role for the October 2026 season of the prequel series "NCIS: Origins," proving that Gibbs' legendary rules are still shaping the franchise today. Which of Gibbs' rules do you think is the most important? #ncis #markharmon #leroyjethrogibbs #ncisorigins #tvshows - @spainadur