In the season nine finale, "Till Death Do Us Part", a bomb blast at NCIS headquarters occurs with Gibbs tackling Abby to the floor in her lab. In the episode "Extreme Prejudice", Gibbs goes after Harper Dearing, cornering the terrorist in a home in West Virginia, and when the man is about to use his gun, Gibbs stabs him, killing him.
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 Di Nozzo, Mc Gee, and Bishop, supported by forensic scientist Sciuto and medical examiner Dr. In the episode "Bête Noire", Gibbs comes face to face with terrorist Ari Haswari and tries to kill him but fails.
He joined NIS, which later became NCIS, after his wife Shannon and only daughter Kelly were murdered in 1991.
He later traveled to Mexico and murdered the drug dealer responsible, a crime he kept concealed for twenty years.
He enlisted in the Marine Corps in 1976 and became a Scout Sniper.
After serving tours of duty in Panama and Iraq, he retired from the Marine Corps with the rank of Gunnery Sergeant.
Gibbs is often shown in his basement building boats, at least one of which he names after his daughter; another is named 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 long-distance head shot of his family's murderer, who was driving a moving vehicle, at 1200 yards, in "Deliverance" by a file read by Director Leon Vance, and in "Jeopardy" when he hits a kidnapper with a very swift killshot to the forehead taken while kneeling inside a car trunk, with his left hand.
In "Truth or Consequences", Gibbs saves his entire team by shooting the leader of a terrorist cell with a killshot after Di Nozzo and Mc Gee get captured looking for Ziva.
The series premiered on September 23, 2003 featuring an ensemble cast which has included Mark Harmon, Sasha Alexander, Michael Weatherly, Cote de Pablo, Pauley Perrette, Sean Murray, Wilmer Valderrama, Jennifer Esposito, Emily Wickersham, Brian Dietzen, Duane Henry, Lauren Holly, Rocky Carroll, and David Mc Callum.