NCIS has been part of the CBS primetime lineup for 18 seasons, with the network airing more than 400 episodes.  

The procedural is seen in more than 200 countries and territories around the globe and has been at the top of the ratings for years.

A few months before NCIS premiered in September 2003, CBS introduced the agency and its main characters via a backdoor pilot in another drama.  

In a two-part season 8 episode of JAG — titled “Ice Queen” and “Meltdown” — Commander Harmon Rabb (David James Elliott) was a murder suspect in a case that NCIS was investigating.

That’s when fans first met NCIS director Thomas Morrow (Alan Dale) and Special Agent in Charge Leroy Jethro Gibbs (Mark Harmon).  

As well as Dr. Donald “Ducky” Mallard (David McCallum), Anthony DiNozzo (Michael Weatherly), and Abby Sciutto (Pauley Perrette). 

Sean Murray (Timothy McGee) didn’t join the cast as a series regular until season 2. And Cote de Pablo’s Ziva David didn’t show up until season 3.

So, the show was essentially called Navy Naval Criminal Investigative Service. Why such a redundant name? It was because CBS wasn’t sure their audience knew what the NCIS acronym stood for.