NCIS is one of the highest rated dramas on television.
The series follows a team of the Naval Criminal Investigative Service Major Case Response Team special agents. This is the primary law enforcement and counterintelligence unit of the United States Department of the Navy.
The Special Agent in charge of the squad is Leroy Jethro Gibbs. He's portrayed by fan favorite Mark Harmon. He leads the unit on cases that include terrorist threats and kidnappings, domestically and sometimes abroad.
By his side throughout has been Michael Weatherly as Tony DiNozzo, a very special agent as he likes to remind us, and by Sean Murray's Tim McGee, often maligned by Tony's wise cracks but always invaluable.
Sasha Alexander and Cote de Pablo played agents Kate Todd and Ziva David, respectively, for the first 10 seasons of the show, before their vacancy was filled by Emily Wickersham as Ellie Bishop.
Pauley Perrette as over-caffeinated forensics wiz Abby Sciuto, Rocky Carroll as NCIS Director Leon Vance, and David McCallum as medical examiner Donald "Ducky" Mallard round out the team.
The series has defied typical TV trends by becoming increasingly popular over time, and has spawned a hugely successful spinoff in NCIS: Los Angeles (NCIS itself was introduced as a backdoor pilot on JAG).
This fall, NCIS: New Orleans, like Los Angeles introduced on an episode of NCIS, and produced by Harmon and NCIS show-runner Gary Glasberg, will also premiere on CBS.