List of NCIS characters

Supervisory Special Agent Leroy Jethro Gibbs (Mark Harmon) was born in Stillwater, Pennsylvania, to Jackson and Ann Gibbs. He enlisted in the Marine Corps in 1976 and became a Scout Sniper. After serving in Panama and Iraq, he retired from the Marine Corps with the rank of Gunnery Sergeant. He joined NIS, which later became NCIS, after his wife Shannon and only daughter Kelly were murdered in 1991. He later travelled to Mexico and murdered the drug dealer responsible, a crime he kept concealed for twenty years. Since then, he has been married and divorced three times, and is single, although he has had a number of romantic relationships since his last divorce.

Gibbs leads a Major Case Response Team (MCRT) consisting of field agents Timothy McGee, Ellie Bishop, and Nick Torres, supported by medical examiner Dr. Jimmy Palmer, psychologist and NCIS Agent Jack Sloane, forensic scientist Kasie Hines, and sometimes with the assistance of his good friend and former medical examiner Ducky Mallard. In the episode "Bête Noire", Gibbs comes face to face with terrorist Ari Haswari and tries to kill him but fails. Finding Ari later becomes an obsession for Gibbs after Ari shoots and kills original team member Kate Todd in front of Gibbs and DiNozzo in the season two finale, "Twilight". Gibbs often shows frustration with his team (particularly DiNozzo for rambling or McGee for getting sucked into technical rambling) by slapping them over the back of the head, an action that is later shared between team members and known as a "headslap" or "Gibbs-slap". He mostly suspended doing this however in season 14 and onward since DiNozzo left the agency, neither with McGee as the new senior field agent and DiNozzo successor nor with new agent Nick Torres, who often displays a variation of DiNozzo's behavior that "earned" him his headslaps previously.

Gibbs is often shown in his basement building boats, one of which he names after his daughter and another after one of his ex-wives. In the episode "Blowback", when confronting "Goliath" on the plane about "ARES", Gibbs reveals he is a Virgo. He is an expert sniper, as evidenced in "Hiatus" with flashbacks of him hitting a head shot at 1,200 yards of his family's murderer, who was driving a moving vehicle, and in "Jeopardy" when he hits a kidnapper with a very swift shot to the forehead taken with his left hand while kneeling inside a car trunk. In "Truth or Consequences", Gibbs saves his entire team by shooting the leader of a terrorist cell after DiNozzo and McGee get captured looking for Ziva.

Gibbs has developed a fatherly relationship with most of his team members, especially Abby Sciuto. When she left in "Two Steps Back", she didn't say goodbye to him in person because of this and instead expressed her reasons for leaving in a letter. He also showed fatherly affection towards Ziva, Tony, McGee, Bishop, and Torres on several occasions. Examples of this include: defending DiNozzo against his father and calling his then senior agent "the best young agent he ever worked with" in "Flesh and Blood"; calling Ziva "kid" in "Safe Harbor"; giving McGee the watch his father had given him on the day of his wedding with Shannon in "Something Blue" when McGee married Delilah; following Bishop to Oklahoma in "Blood Brothers" to help her deal with the end of her marriage; and having dinner with Torres to help him cope with his father abandoning him again in "Sangre".

One of Gibbs' longest lasting relationships on screen is his friendship with Tobias Fornell. The two had known each other since before the show started and had gotten to know each other when Fornell was about to marry Gibbs' second ex-wife Diane. Gibbs warned Fornell that Diane would leave him and plunder his accounts—which happened eventually. Over the course of the show, Fornell and Gibbs often butted heads but their friendship became so strong over time that even after Gibbs ended Fornell's career as an FBI agent in "Burden of Proof" through court testimony the two were able to forgive each other and rekindle it. In "Daughters" Fornell forces Gibbs to take the case of Fornell and Diane's daughter Emily who had overdosed on drugs despite not falling in the jurisdiction of NCIS.

At the end of "Daughters", Gibbs is visited by Ziva who he believed had died when her farm house was hit by a missile in "Dead Letter". While he and Ziva are on the run from a terrorist group that tries to kill Gibbs in order to force Ziva to join them, Ziva confronts Gibbs about him not looking for her after her apparent death. He later admits to her in "Into the Light" that he was afraid to go looking for her and find out that she was indeed dead (a sentiment he repeats to Sloane an episode later).

The relationship between Gibbs and Sloane is different from those he has with the rest of his team. The two are friends but the other team members, most openly Torres, have noted that the two have "a thing". In "What Child Is This?" the two are shown to be pretty close to the point that they apparently cuddle in public. This, however, led nowhere, which Sloane herself laments in "Going Mobile". That episodes ends with Gibbs replacing her rorschach test painting with that of an elephant in reference to her calling their non-existing "thing" "the elephant in the room" earlier in the episode.

He held position as MCRT team leader up until March 2021 when he was suspended for assaulting a dog murderer which leaves his second-in-command, NCIS Special Agent Timothy McGee to succeed him as the agent in charge of the MCRT.

In June 2021, Gibbs resigned from the team and NCIS for good, opting to remain in Alaska instead of returning to Washington, D.C., and ultimately resuming his career as the leader of the MCRT and also an NCIS Special Agent instead of Supervisory Special Agent. This is because he managed to find the happiness that he had not felt since Shannon and Kelly's deaths.

Until season 19's "Face the Strange", Harmon was the only main actor to appear in every episode of the series. Provided by Wikipedia