Leroy Jethro Gibbs (AKA Gunnery Sergeant Alvin Thomas or Leland Robert Spears) is a former Gunnery Sergeant in the United States Marine Corps who is now an NCIS Special Agent assigned to the Navy Yard in Washington D.C. and who is also the current leader of the main NCIS Major Case Response Team.
Born in the small town of Stillwater, Pennsylvania, Gibbs was the only child of US Army Air Force veteran Jackson Gibbs and his wife, Ann Gibbs. He was named after Leroy Jethro Moore, his father's best friend and business partner.
After graduating from high school, Gibbs was given the option of going to college but chose to join the United States Marine Corps instead.
He went through boot camp at the Marine Corps Recruit Depot, Parris Island.
As a junior enlisted man, he was stationed at Camp Lejeune as a Military Policeman.
Following his training, Gibbs became a Scout Sniper and did various tours of duty, including Panama which saw him participating in Operation Just Cause, and later with the 1st Battalion 1st Marines in the Persian Gulf with the team a part of Operation Desert Storm.
Some time later, Gibbs was dispatched to serve with the Marines while promising Shannon that he would come back safe.
As a Marine, Gibbs befriended Bushnell, who in 2005 was a Colonel with United States Southern Command, future Senator Patrick Kiley, and Charles T. Ellison (who would one day become the Commandant of the Marine Corps), three people he would once encounter during his time as an NCIS agent.
While serving in Desert Storm which had taken him overseas, Gibbs received that both Shannon and Kelly were dead, having been murdered which left him grief-stricken and devastated.
Despite that, Gibbs opted to stay and fight but was ultimately wounded during a fight and was left comatose for nineteen days. He also received the Purple Heart for his actions.
During his recovery process, Gibbs visited the graves of his dead wife and daughter. He also met NIS agent Michael Franks who was investigating their deaths.
Once he had recovered, Gibbs personally traveled to Mexico and shot dead Pedro Hernandez in revenge. He was investigated for the shooting by Lieutenant Lara Macy of the USMC Military Police, but she closed her investigation after learning about the circumstances that led to the shooting.
In 1992, Gibbs was honorably discharged from the United States Marine Corps with the rank of Gunnery Sergeant.
Following that, Gibbs joined the Naval Investigative Service- NIS, presumably having been impressed and inspired by Franks's actions. He became a Probationary Agent with Franks handling most of Gibbs's own training.
Gibbs also met Vera Strickland, Franks's partner at the time.
After Franks had retired from NIS/later NCIS in 1996, Gibbs began working as an undercover agent. He also traveled the world while serving as a training officer to NCIS Special Agent Stanley Burley.
In 1999, NCIS Special Agent Riley McCallister sent Gibbs to Europe, the destination being Paris, France where Gibbs met NCIS agents William Decker and Jennifer Shepard, as well as Medical Examiner Dr. Donald Mallard.
Gibbs and Shepard became partners and eventually lovers with the relationship soon ending after Jenny left Gibbs a "Dear John" letter.
Gibbs was later assigned to Moscow where he worked alongside NCIS Special Agent G. Callen.
Later, Gibbs served as an Agent Afloat on board an unnamed Navy ship in the Mediterranean. Upon his deployment ending, Gibbs returned home and found his then-wife, Rebecca Chase in bed with another man. As such, Gibbs and Rebecca divorced.
In 2001, Burley became an Agent Afloat while Gibbs was assigned to the NCIS Headquarters located in the Navy Yard in Washington D.C.
While there, Gibbs formed his own team originally composed of former Baltimore Police Department Detective Anthony DiNozzo, Forensics Specialist Abigail Sciuto and Ducky with former FBI agent Vivian Blackadder later joining the team a few months later after the attack on the U.S.S. Cole.
JAG Season 8
NCIS Season 1
NCIS Season 2
NCIS Season 3
NCIS Season 4
NCIS Season 5
NCIS Season 6
NCIS Season 7
NCIS Season 8
NCIS Season 9
NCIS Season 10
NCIS Season 11
NCIS Season 12
NCIS: New Orleans Season 1
NCIS Season 13
NCIS: New Orleans Season 2
NCIS Season 14
Hand to Hand Combat
Gibbs has displayed some knowledge or possible medical training which was seen in the Season 12 premiere episode, "Twenty Klicks" where he treated the injuries helicopter pilot Navy Lieutenant Commander Hannah Banks had sustained from the helicopter being shot down.