NCIS American police procedural drama television series revolving around a fictional team of special agents from the Naval Criminal Investigative Service. CBS. 2003 - Present.

This dramatic series about criminal investigations within the U.S. Navy has become the most-popular scripted drama on American television (and around the world), leading to an equally-successful sister series.

NCIS, which stands for Naval Criminal Investigative Service, is a spin-off of the military legal drama JAG, which first aired on NBC in 1995. It featuring David James Elliott and Catherine Bell as a pair of staffers in the Judge Advocate General’s office with a long-running attraction for each other. But NBC let JAG go after one season; CBS then picked up the show–which became popular with its older audience--and ran through 2005.

In early 2003, a two-part episode of JAG aired as the NCIS pilot; it did well in the ratings and led to the series that fall. Originally titled Navy NCIS when the new show premiered in the fall of 2003, it quickly became a top-20 hit, surpassing the now-fading JAG, and the title was shortened to just NCIS in 2004.

The investigators of NCIS look into crimes involving members of the Navy and the Marines, led by Supervisory Special Agent Leroy Jethro Gibbs, played by Mark Harmon. His staff includes Special Agent Anthony DiNozzo (Michael Weatherly), Special Agent Timothy McGee (Sean Murray) and Catlin Todd (Sasha Alexander, who was killed at the end of the first season and replaced by Cote de Pablo as Probationary Special Agent Ziva Davis). Others in the cast include David McCallum as chief medical examiner Donald “Ducky” Mallard; medical assistant Jimmy Palmer (Brian Dietzeri) and Pauley Perrette as forensic specialist Abigail Sciuto. Because of its format, many critics see NCIS as a military version of CBS’ very popular CSI and its spin-offs. It’s likely the familiar premise helped NCIS achieve high ratings, along with star Harmon–a familiar and well-liked face on television through various series, starting with St. Elsewhere in the 1980's. In fact, unlike many series, NCIS has increased its audience over the years, and has more than held its own in head-to-head competition against Fox’s wildly popular American Idol.

Like JAG, NCIS was created by Donald Bellisario, the man who also created and Quantum Leap. He was also the executive producer and show runner. But reports of what has been described as Bellisario’s “chaotic management style” caused friction between him and Harmon. (The actor reportedly didn’t like Bellisario's habit of last-minute script changes, requiring long days of shooting.) In 2007, Bellisario left NCIS to develop new series for CBS. As it turned out, the first of those new shows was a spin-off of NCIS. Dubbed NCIS: Los Angeles, it features Chris O’Donnell and rapper/actor LL Cool J as agents who investigate cases out of the West Coast. Also in the cast are Peter Cambor, Eric Crhistian Olsen, Daniela Ruah and Academy Award-winning actress Linda Hunt (“The Year of Living Dangerously”) as Hennetta “Hetty” Lange, the special projects manager for the Office of Special Projects. Slotted after its parent on Tuesday nights, it has also become a top ten hit. Some critics have faulted NCIS:LA for its familiar feel. But then, familiarity usually breeds popularity, as the success of both NCIS shows have proven.