Anthony "Tony" D. DiNozzo Jr., (or "Junior" by his father, Anthony DiNozzo Senior or Very Special Agent Anthony DiNozzo) was the Senior Field Agent on the NCIS Major Case Response Team led by Leroy Jethro Gibbs with Tony also serving as the second-in-command of the team.
In rare occasions where Gibbs was usually absent or elsewhere, Tony automatically became the temporary leader of the team.
After being with NCIS for fifteen years, having first joined the agency in 2001, Tony resigned from NCIS for good in May 2016 to care for his daughter, Tali David-DiNozzo.
Born in an unknown state, presumably New York, DiNozzo was the son of wealthy businessman Anthony DiNozzo Senior and an unnamed woman with the family residing in Long Island, New York and also harboring some wealth although the degree of wealth they had was never revealed.
At the age of five, young DiNozzo endured nightmares about vampires due to his mother going through a phase involving Louis XV that inspired the decor of his room.
During his childhood, DiNozzo also owned some Sea Monkeys until his mother accidentally drank them, having confused their sea castles with her mint julep.
Due to the fact that his father was a Civil War re-enactor, young Tony was forced to carry the poop bucket during scenes, causing the other re-enactors to call Tony "their little poo boy".
Presumably at some point, DiNozzo's mother, who may have been an alcoholic like her husband subsequently died and this triggered DiNozzo's own miserable childhood as he was left behind in a hotel room at one point.
DiNozzo Senior would later remarry, choosing various women who would become young Tony's stepmothers with Tony having no positive or pleasant memories of any of them.
At some point, DiNozzo as a teenager was shipped off to boarding school.
After finishing either boarding school or high school, DiNozzo then attended Rhode Island Military Academy.
He later attended Ohio State University, graduating with a Bachelor of Arts degree in Physical Education.
During his time at Ohio State, he was on the varsity basketball team and made it to the Final Four before losing to UCLA. He later participated in a football game leading a team against one from Michigan that was led by Brad Pitt. Tony broke his leg during the game which was revealed to have been broken by Brad alone.
At some point, Tony was also in the Ohio State Alpha Chi Delta class of 1989. He also received a combined score of 950 on his SATs.
While in Ohio State, Tony saw a townhouse on fire and rushed inside, finding a young boy inside a closest.
As Tony carried the boy out of the building, the boy mentioned his sister, Amber and as Tony attempted to save Amber, a part of the ceiling fell in front of him and as such, Tony decided to leave Amber and save the boy instead.
It was later revealed that Tony had a choice: save the boy or risk their lives to save Amber. Tony ultimately choosing to flee the building with the boy in tow.
Upon becoming a Detective, Tony spent two years in Peoria and Philadelphia before moving to Baltimore which was revealed in the Season 1 episode, High Seas (episode).
While at Baltimore, Tony ran into his future boss: Leroy Jethro Gibbs and the two sides worked together on a money laundering case.
Tony eventually discovered that his partner, Danny Price was a dirty cop which ultimately prompted Tony to resign from Baltimore PD for good and join NCIS instead, Gibbs having suggested it to him earlier.
Tony eventually joined NCIS and presumably began as an NCIS Probationary Agent before eventually being promoted to the rank of Senior Special Agent of the team.
JAG Season 8
Tony made his debut appearance in the JAG Season 8/NCIS backdoor pilot episode, Ice Queen (episode) where at the time of his introduction, he was the Senior Special Agent of the main NCIS Major Case Response Team led by NCIS Special Agent Leroy Jethro Gibbs which also included Agent Vivian Blackadder, Dr. Donald Mallard and Forensic Scientist Abigail Sciuto.
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: New Orleans Season 1
NCIS Season 12
NCIS: Los Angeles Season 7
NCIS Season 13
Prior to joining NCIS, Tony worked as a Police Detective in Peoria and Philadelphia as well as Baltimore but upon discovering that his Baltimore partner was in fact corrupt, Tony chose to resign from the Baltimore Police Department force for good and join NCIS instead which occurred in 2001.
Presumably, after a few months, Tony was promoted from Probationary Agent to NCIS Special Agent before becoming Senior Special Agent of the main NCIS team, a rank he held up until his resignation from the team in May 2016.
As an NCIS Special Agent and also the Senior Agent of the Major Case Response Team, Tony was one of the most skilled Agents associated with NCIS in general.
He was trained to process crime scenes and interrogate any possible suspects too.
He was also extremely skilled in undercover work as evident by former NCIS Director Jenny Shepard choosing him for an undercover operation that lasted for most of NCIS Season 4.
Like Gibbs, DiNozzo was old school in terms of using traditional methods to solve a case but in recent years, DiNozzo had also begun using technology as well.
Like all NCIS Special Agents, Tony was trained in the use of a firearm with his primary weapon of choice being a SIG-Sauer P228.
Tony was skilled at interrogating various suspects that the NCIS team come across. He was always seen interrogating suspects usually by himself or alongside Gibbs, McGee, Ziva and Bishop.
Tony was skilled in lock-picking.