As "NCIS" continued, Gibbs kept adding to his list of rules. We know that he has nearly 100 of them, but unfortunately, even ...

Leroy Jethro Gibbs (Mark Harmon) lived by his rules on NCIS. For 19 seasons, Gibbs spouted his guidance to his team of special agents, giving them a handbook to live and work by.

If you’re going to be on Gibbs’ (Mark Harmon) team on NCIS, live by these. Rule #1: Never let suspects sit together. Other Rule #1: Never screw over your partner.

Gibbs' Rules are a part of NCIS, but Origins star Austin Stowell reveals the real-life rule he learned from "sage" Mark Harmon on the set of the prequel. Skip to main content.

When you take into account Gibbs' background as a former U.S. Marine Corps Scout Sniper, Rule 9, "Never go anywhere without a knife," makes much more sense.

Actor Harmon left the series in 2021, but his character's list of advice lives on with the prequel series NCIS: Origins, and the NCIS flagship, whose 22nd season concludes on May 5. "My wife believed ...