List of NCIS episodes

NCIS and its characters were originally introduced in a two-part episode of the CBS television series JAG in April 2003. The show premiered on September 23, 2003, in the United States.

Created by Donald P. Bellisario and Don McGill, and executive produced by Bellisario, Shane Brennan, Gary Glasberg, George Schenck, Frank Cardea, and Steven D. Binder, NCIS stars Mark Harmon as Supervisory Special Agent Leroy Jethro Gibbs, and Gary Cole as Supervisory Special Agent Alden Parker in charge of NCIS' Major Case Response Team. Based out of Washington, D.C., the team includes special agents Caitlin Todd (Sasha Alexander), Anthony DiNozzo (Michael Weatherly), Timothy McGee (Sean Murray), Ziva David (Cote de Pablo), Eleanor Bishop (Emily Wickersham), Alexandra Quinn (Jennifer Esposito), Nicholas Torres (Wilmer Valderrama), and Jessica Knight (Katrina Law), forensic specialists Abby Sciuto (Pauley Perrette) and Kasie Hines (Diona Reasonover), medical examiners Jimmy Palmer (Brian Dietzen) and Donald "Ducky" Mallard (David McCallum), medical examiners assistant Gerald Jackson (Pancho Demmings) and SIS attaché Clayton Reeves (Duane Henry). Operational psychologist Dr. Jacqueline Sloane (Maria Bello) assists the team during troubled times, while successive Directors Tom Morrow (Alan Dale), Jennifer Shepard (Lauren Holly), and Leon Vance (Rocky Carroll) command from on high.

Introductory episodes
The program and its characters are introduced during the eighth season of JAG. The JAG episodes, "Ice Queen" and "Meltdown", served as pilot episodes for the show. The character Special Agent Vivian Blackadder (Robyn Lively) does not appear in the series because producer Donald Bellisario felt that "she was a little soft for this kind of role". In October 2003, the two episodes were edited together and aired as "Navy NCIS: The Beginning".

Season 1 (2003–04)

 * Sean Murray (Timothy McGee) first appears episode 7, ("Sub Rosa"), has one scene in (“Eye Spy”), episode 11, then from episode 18-23 has a continuous arc.

Season 2 (2004–05)

 * Sean Murray (Timothy McGee) was promoted to the main cast starting with the episode "See No Evil".
 * Sasha Alexander (Special Agent Caitlin Todd) left the show after the season finale ("Twilight").

Season 3 (2005–06)

 * Cote de Pablo (Ziva David) had a continuous arc starting with the first two episodes ("Kill Ari"), and later promoted to the main cast in the episode "Silver War".
 * Lauren Holly joins the supporting cast as NCIS Director Jenny Shepard. She was promoted to the main cast in the ninth episode ("Frame Up").
 * This is the first season to feature 24 episodes.

Season 5 (2007–08)

 * Rocky Carroll (Leon Vance) had a continuous arc starting with episode 14 ("Internal Affairs").
 * Lauren Holly (Jenny Shepard) left the show after the season finale ("Judgment Day").
 * This season originally consisted of 24 episodes, unfortunately due to the 2007–08 Writers Guild of America strike, but dropped down to contain only 19 episodes at that point.

Season 6 (2008–09)

 * Rocky Carroll (Leon Vance) was promoted to the main cast starting with the episode "Last Man Standing".
 * "Legend" serves as the two-part backdoor pilot for the spin-off NCIS: Los Angeles.
 * This is the first and only season to feature 25 episodes.

Season 10 (2012–13)

 * Brian Dietzen as M.E. Assistant (Jimmy Palmer) was promoted to the main cast as of this season.

Season 11 (2013–14)

 * Cote de Pablo as Special Agent (Ziva David) departed the show after the second episode, "Past, Present, and Future".
 * Emily Wickersham as NSA Analyst and then Probationary Special Agent, (Eleanor Bishop), is introduced in episode nine, "Gut Check", and was later promoted to the main cast in episode twelve, "Kill Chain".
 * "Crescent City" serves as the two-part pilot for NCIS: New Orleans.

Season 13 (2015–16)

 * Episode 12 begins a crossover event that concludes on NCIS: New Orleans season 2 episode 12.
 * Michael Weatherly (Anthony DiNozzo) departed the series after the season finale "Family First".

Season 14 (2016–17)

 * The first season not to feature longtime cast member Michael Weatherly, who left the series after 13 seasons in the thirteenth season finale.
 * Jennifer Esposito (Alexandra "Alex" Quinn) and Wilmer Valderrama (Nicholas "Nick" Torres) join the cast. Jennifer Esposito departed in the season finale.
 * Duane Henry (MI6 Senior Officer Clayton Reeves) was promoted to the main cast in the fifth episode ("Philly").
 * Pandora's Box (Part I) episode begins a crossover event that concludes in NCIS: New Orleans episode, Pandora's Box, Part II.

Season 15 (2017–18)

 * Maria Bello (Jacqueline Sloane) made her series debut in episode 4, "Skeleton Crew", before her promotion to series regular in episode 5, "Fake It 'Til You Make It".
 * Pauley Perrette (Abby Sciuto) and Duane Henry (Clayton Reeves) departed the show in episode 22, "Two Steps Back".

Season 16 (2018–19)

 * Diona Reasonover (Kasie Hines) was promoted to the main cast.
 * Cote de Pablo (Ziva David) made a surprise appearance in the season finale.
 * This is the final season to have 24 episodes.

Season 17 (2019–20)

 * Cote de Pablo (Ziva David) had a recurring role in the season.
 * On March 13, 2020, CBS announced that the filming of season 17 had been suspended due to the COVID-19 pandemic resulting in only 20 episodes being filmed.

Season 18 (2020–21)

 * Maria Bello (Jacqueline Sloane) departed the show in episode 8 "True Believer".
 * Emily Wickersham (Eleanor Bishop) departed the show after the season finale "Rule 91".

Season 19 (2021–22)

 * Katrina Law (Jessica Knight) was promoted to the main cast.
 * Gary Cole (Alden Parker) makes his debut in episode 2 and joins the main cast in episode 3.
 * Mark Harmon (Leroy Jethro Gibbs) departed the show in episode 4 "Great Wide Open", but remains on the title sequence for the remainder of the season, but was removed in season 20.
 * Episode 17 begins a crossover event that concludes on NCIS: Hawaiʻi season 1 episode 18.

Season 20 (2022–23)

 * Episode 1 begins a crossover event that concludes on NCIS: Hawaiʻi season 2 episode 1.
 * Episode 10 begins a crossover event that continues on NCIS: Hawaiʻi season 2 episode 10 and concludes on NCIS: Los Angeles season 14 episode 10.
 * David McCallum (Donald Mallard) made his final appearance in the season finale "Black Sky" before his death.

Season 21 (2024)

 * This is the first season to not feature David McCallum as Ducky Mallard as McCallum died around a week before this season entered production. "The Stories We Leave Behind" paid tribute to him and is dedicated to him.
 * Michael Weatherly (Anthony DiNozzo) returned as a special guest star in the episode "The Stories We Leave Behind," making this his first appearance on the show after his exit in the season 13 finale ("Family First").