Anthony "Tony" D. DiNozzo Jr. or "Junior" by his father, Anthony DiNozzo Senior is 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 is usually absent or elsewhere, Tony will automatically become the temporary leader of the team.
Born in an unknown state, presumably New York, DiNozzo was the son of wealthy businessman Anthony DiNozzo Senior and an unnamed mother.
DiNozzo had a fairly miserable childhood which usually consisted of him being left in a hotel room as revealed in the episode Honor Code (episode).
At some point, young DiNozzo was also shipped off to boarding school which was seen during the Season 12 episode, Cadence (episode).
After finishing either boarding school or high school, DiNozzo then attended Rhode Island Military Academy before attending Ohio State University, graduating with a Bachelor of Arts degree in Physical Education which was revealed in the Season 8 episode, Baltimore (episode).
During his time at Ohio State, he was on the varsity basketball team and made it to the Final Four before losing to UCLA which he revealed to Kate during Dead Man Talking (episode).
While in isolation, during SWAK (episode), Tony talks about a football game between his team and another one from Michigan led by Dr. Brad Pitt- (the doctor who's treating both Tony and Kate with Pitt insisting that he's no relation to the actor of the same name). Tony also reveals that he broke his leg during the game but Pitt corrects him by stating that he actually broke Tony's leg.
In Red Cell (episode), Tony starts to tell a story at his fraternity days before Gibbs cuts him off, threatening both Tony and Kate with the news that he will fire them if Gibbs himself hears any more discussions of Spring Break or college.
In Child's Play (episode), Tony mentions receiving 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 to flee the building with the boy in tow.
The young boy, still resenting Tony for refusing to save his sister later got a job at the Baltimore Arson Unit and didn't meet Tony until the Season 9 episode, Rekindled (episode).
This event was what later prompted Tony to become a Detective.
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 began work as an NCIS Special Agent before eventually becoming the Senior Special Agent of the team, a position he holds to this day.
JAG Season 8
DiNozzo 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.
DiNozzo also helped process the crime scene at Protomac Park where the remains of JAG Lieutenant Loren Singer were discovered.
While Gibbs and Viv headed to JAG to interview Singer's colleagues, DiNozzo was tasked with finding the bridge where Singer had fallen into the river and eventually drowned.
NCIS Season 1
DiNozzo made his official debut appearance in the main NCIS series in the Season 1 premiere episode, Yankee White (episode) where he first called Gibbs to inform him that a Navy Commander had died on board Air Force One, forcing the plane into an emergency landing at an airport in Wichita, Kansas.
NCIS Season 2
In Heart Break (episode), it was revealed that Tony had been in a relationship with Paula Cassidy for a few months although she had been on assignment as an Agent Afloat on the USS Kennedy although after the case concerning Navy Commander Michael Dornan, it's possible that Cassidy herself ended the relationship.
NCIS Season 3
In Kill Ari Part 1 (episode), Tony, like the rest of the team struggled to come to terms with Kate's murder.
To help cope with his grief, Tony imagined Ghost Kate with Kate's ghost even wearing various outfits such as a Catholic schoolgirl uniform.
In Boxed In (episode), it was revealed that Tony's blood type was A.
In Untouchable (episode), Tony revealed that he had owned some Sea Monkeys as a child until his mother had accidentally drunk them, having gotten the Sea Monkeys with her own mint julep.
When Gibbs was left in a coma after being caught in a bomb blast in the Season 3 finale episode, Hiatus Part 1 (episode), Tony took over the running of the team, becoming the team leader as they sought to track down a terrorist.
In Hiatus Part 2 (episode), the team attempted to arrest PinPin Pula, only to ultimately fail as PinPin later set off a bomb, killing himself and destroying a ship full of Naval personnel which had Gibbs quitting NCIS, essentially leaving the team in Tony's hands.
NCIS Season 4
With Gibbs having retired, Tony was promoted to the rank of Team Leader while McGee was promoted to Senior Field Agent although Ziva's role on the team remained unchanged while NCIS Special Agent Michelle Lee joined the team.
At some point, the team also investigated a case concerning Renny Grant.
In Shalom (episode), Tony returned from a security conference and handed out gifts to the team. He later clashed with FBI Special Agent Ron Sacks or "Slacks" when it was revealed that Ziva was wanted for espionage and murder.
Tony later went off the grid to help Ziva and reunited with Gibbs.
Once Gibbs returned in Escaped (episode), Tony stepped down, returning to his original Senior Field agent status while helping NCIS Director Jennifer Shepard with an undercover operation at her request with the operation involving him "befriending" Jeanne Benoit, the daughter of international arms dealer, René Benoit AKA "The Frog".
In the Season 4 episode, Grace Period (episode), Tony befriended Cassidy after she lost her team in a surprise suicide bombing and was ultimately devastated when she sacrificed herself to stop a suicide bomber from attacking the NCIS team.
NCIS Season 5
Not wanting Tony and Ziva to be involved, Jenny gave them the rest of the day off while she and Michael Franks investigated the Agent's supposed death by natural causes while, Tony and Ziva, uneasy about being given the brush-off enlisted their colleague, Timothy McGee to find Jenny which he did.
However, by the time they got to the abandoned diner, they discovered a lot of bodies inside, Jenny's among them.
Tony then knelt down and checked Jenny's neck for a pulse but found none and as Tony and Ziva stood there, grieving, Gibbs rang with Tony answering the phone and presumably telling Gibbs that Jenny was dead.
Hours later, after they had returned in D.C., Tony, still consumed with guilt began drinking as a means of coping his guilt. He, Tony, Ziva and Gibbs were later called into Vance's office, Vance having been appointed the new NCIS Director and the team were stunned when Vance reassigned them to new positions: Ziva would be returning to Israel, McGee would be moving to Cyber Crimes while DiNozzo was to become an Agent Afloat on the USS Ronald Reagan.
NCIS Season 6
A few months later, DiNozzo was still at sea but now as the Agent Afloat on the USS Seahawk.
However, after the issue which led to his assignment on the ship was resolved, he was reassigned to his original team back at NCIS headquarters in Washington, D.C. where he remains to this day.
In Legend Part 1 (episode) and Legend Part 2 (episode), the two backdoor pilot episodes for the spin-off series, NCIS: Los Angeles, Tony began to suspect that Ziva was not truly loyal to NCIS and that she was lying to the team.
He enlisted Abby's help in uncovering Rivkin's true identity before later swearing Abby to secrecy, presumably so that he could do his own investigating without alerting his own team as well as the Office of Special Projects in Los Angeles.
In Semper Fidelis (episode), after learning that Rivkin had been responsible for killing Abin Tabal, the leader of the terrorist cell in Los Angeles and also ICE agent Thomas Sherman, not realizing that the ICE agent's death had been accidental, Tony took matters into his own hands and sought to arrest Rivkin for the two killings but unfortunately, the supposed arrest turned into a massive brawl when Rivkin fought back.
During the fight, both men inflicted injuries on each other with Rivkin managing to break Tony's left arm with Tony later ending the fight by throwing both himself and Rivkin into a glass table.
Tony then crawled for his gun and sought to reason with Rivkin but upon discovering that Rivkin planned to stab him with a piece of glass, Tony responded by firing off three shots from his gun which caused Rivkin to hit the ground, unconscious.
This ultimately caused Ziva to enter the apartment, her own gun drawn and for a second, the two engaged in a tense stand-off with each other.
In Aliyah (episode), the stand-off came to an abrupt end as Ziva holstered her gun before performing CPR on a barely conscious Rivkin while yelling at a badly wounded Tony to call an ambulance.
A few hours later, at the hospital, Gibbs arrived and sent Tony back to write up a report on what happened with Ziva emerging from the waiting area seconds later where she informed Gibbs that Rivkin had succumbed to his injuries and died, stating that Tony had killed Rivkin.
NCIS Season 7
NCIS Season 8
NCIS Season 9
However, it was also discovered that Sean Latham, a supposed friend of Jarvis's was the true traitor, having manipulated Jarvis into believing that Cade was guilty.
NCIS Season 10
NCIS Season 11
In Past, Present and Future (episode), after learning that Ziva had gone into hiding, Tony personally headed to Israel in the hope of tracking Ziva down.
After months of searching which also saw Tony growing a beard as well, Tony later used all the clues he had gathered from Ziva's pattern and eventually tracked her down at the country house where she had been born and attempted to have her return to the United States with him but despite his best efforts, Ziva ultimately chose to stay behind in Israel.
In Once a Crook (episode), as a result of Ziva's abrupt and permanent departure from the team as well as NCIS itself, Ziva having chosen to stay in Israel, Tony, still struggling to cope with Ziva leaving became insomniac which saw him not sleeping for the last days. This in turn ultimately hampered Tony's own ability to focus on the case concerning an informant of his who Tony had met while working as a cop in Baltimore and also the current investigation concerning the murder of Navy Petty Officer First Class Andrew Wells.
NCIS: New Orleans Season 1
DiNozzo appeared in the NCIS: New Orleans Season 1 episode, "Carrier".
NCIS Season 12
In the Season 12 premiere episode, Twenty Klicks (episode), Tony took charge of the search for Gibbs and McGee who had gone missing after their helicopter had been shot down.
In the Season 3 premiere episode, Kill Ari Part 1 (episode), it was revealed that Tony comes from a wealthy family located in Long Island, New York.
In the Season 4 episode, Twisted Sister (episode), it was also revealed that Tony was or is an only child but in the Season 2 episode, Black Water (episode), Tony reveals that he's been cut off from the family fortune, causing Gibbs to remark that he knows what Tony's parents know what their son would do with the money which has Tony stating that he can't even get an advancement on the will although in the Season 6 episode, South by Southwest (episode), Tony reveals that his mother is dead.
In the Season 1 episode, Bête Noire (episode), Tony tells Kate that when he was five, his mother went through a phase involving Louis XV that inspired the decor of his room and also gave him nightmares about vampires.
In Season 3's Untouchable (episode), Tony states that he once owned some Sea Monkeys until his mother accidentally drank them, having confused their sea castles with her mint julep much to Ziva's amusement while in Silver War (episode), he states that he strongly dislikes anything concerning the Civil War due to the fact that his father was a Civil War re-enactor and young Tony was forced to carry the poop bucket during scenes, causing the other re-enactors to call Tony "their little poo boy".
In the Season 2 episode, Chained (episode) and the Season 4 episode, Witch Hunt (episode), Tony hints that his father was abusive and an alcoholic. In the Season 7 episode, Flesh and Blood (episode), Tony's father, Anthony DiNozzo Senior is introduced and it's revealed that he and his son share similar personality traits, the two being that both of them flirt with women. It's later revealed that Tony's father is broke and a con artist pretending to be rich when he is not.
It's also discovered that after his mother died, Tony and his father very rarely spent any kind of time together and rarely spoke to another which is what has caused their relationship to become so strained over the years. Tony also spent the rest of his childhood in a series of boarding schools and summer camps.
In the Season 3 episode, Honor Code (episode), Tony reveals that he was once left in a hotel room for two days while his father attended a supposed business meeting and that DiNozzo Senior didn't notice Tony was missing until he got the room bill.
Tony mentions that he has a button-collecting grandfather who lost him one thousand shares in a dot.com company as well as a cousin Petey as revealed during the Season 1 episode, The Good Samaritan (episode). In the Season 2 episode, Conspiracy Theory (episode), Tony mentions that he had an uncle who was once a successful businessman but was apparently found at golf course, digging holes in the ground and looking for mole people.
In Season 3's Head Case (episode), Tony also states that he has an uncle Vincenzo who is a butcher on Long Island. In the Season 6 episode, South by Southwest (episode), Tony reveals that he had a third uncle name Clive Paddington who was wealthy and had recently died as well as a cousin named Crispin.
Tony is a street-wise, sarcastic and un-serious person with his behavior towards women verging on chauvinistic although he has toned it down in recent years. He has a habit of flirting with every women he meets much to his colleagues's annoyance.
He also has no understanding of personal boundaries whatsoever and has been known to dig into the private lives of his teammates, examples being Caitlin Todd, Ziva and Timothy McGee.
In recent years, though, Tony's behavior has matured albeit minutely.
As a movie buff, Tony is well-known for quoting various pieces of dialogue from the movies and TV shows he has seen.
He often sees parallels between the cinema and his everyday life. Tony is a fan of the television series "Magnum P.I" and Airwolf, both of which were produced by Donald P. Bellisario who created NCIS.
Despite Tony's childlike behavior, there are times where he can take things seriously and act just as tough as Gibbs is.
Tony's co-workers often display visible frustration with his childlike behavior, but throughout the series Tony has been shown to be very loyal to his coworkers at NCIS, particularly his supervisor, Leroy Jethro Gibbs.
As the Senior Field agent of the team, Tony often likes to throw his weight around and leave most of the grunt work to the younger, less-experienced agents including Ziva or McGee. He also usually attempts to take credit for something one of his colleagues has done which is shown in the Season 1 episode, Dead Man Talking (episode) when he pretends to be the one who's been searching for a suspect's name and her address when it was actually McGee who has done all the hard work in the first place although Gibbs is able to figure it out despite DiNozzo not saying anything and then "asking" McGee to go make a coffee for him.
In addition, Tony also likes pulling rank, stating many time that he outranks the other members of the team although this has sometimes worked against him.
DiNozzo is a man in his mid forties with brown hair and green eyes.
He often wears business suits complete with ties and trousers as well as polished shoes.
He also even wears silver watches at some point and has continued to do so although during some episodes of Season 9, he was seen wearing a sports-styled watch before returning to wearing his silver watch.
In his debut appearance in "Ice Queen", DiNozzo was originally seen wearing a single cardigan or a jumper with trousers and shoes.
As NCIS progressed, he occasionally switched between casual clothing such as shirts or trousers and business suits complete with dinner jackets and ties.
In Season 1, DiNozzo's hair had grown down to the point that it stretched presumably his ears with even a fringe appearing but in later seasons, he cut it and has opted to keep it shortened although his hair had grown slightly long by the end of NCIS Season 8.
He later had cut it again and has kept it short since then.
While searching for Ziva, Tony eventually grew a beard which he later shaved off before returning to the United States.
In the early years of NCIS, DiNozzo was seen wearing glasses, prime examples being the JAG Season 8/NCIS backdoor pilot episode, Ice Queen (episode) and once again in the Season 1 episode, The Curse (episode) albeit briefly.
He later stopped wearing them for good, presumably due to the fact that he may have gotten laser eye surgery to improve his eyesight.
In Season 1, DiNozzo was seen wearing a brown leather holster with two holsters where he kept his SIG-Sauer and back-up weapon, possibly due to the fact that they could be in a place where he could easily access them, especially if time was of the essence or if he was in danger.
In Season 7, DiNozzo was seen wearing a newer version of the leather holster which was back. This also contained his SIG-Sauer and back-up weapon.
In recent years, DiNozzo has been seen wearing it again, the most recent appearance being the Season 12 episode, House Rules (episode).
As an NCIS Special Agent and also the Senior Agent of the Major Case Response Team, Tony is one of the most skilled Agents associated with NCIS.
He is trained to process crime scenes and interrogate any possible suspects too.
He is 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 is old school in terms of using traditional methods to solve a case but in recent years, DiNozzo has also begun using technology as well.
Tony's specialty is going undercover and he is so skilled at it that Gibbs regards Tony as a "born operator".
This skill which has been honed to perfection has enabled Tony to go undercover many times, especially if it requires getting information about a suspect or person of interest in a case that the team are investigating without tipping off the suspects themselves, examples are in the Season 1 episode, Split Decision (episode) where he poses as a rogue weapons-dealer, unknowingly uncovering an Alcohol, Tobacco and Firearms operation in the process.
His undercover skills are so good that Director Jenny Shepard chose him to help her with a top-secret undercover operation concerning her personal enemy, the Frog.
Tony is fluent in Spanish and Italian.
Like all NCIS Special Agents, Tony is trained in the use of a firearm with his primary weapon of choice being a SIG-Sauer P228.
Tony is skilled at interrogating various suspects that the NCIS team come across. He has been seen interrogating suspects usually by himself or alongside Gibbs, McGee, Ziva and Bishop.
During the entire run of NCIS, Tony consistently speaks at great length about women. He pursues girls on a regular basis, typically indiscriminately, though he has shown an aversion to women who don't shave. Few of these relationships ever progress beyond several dates (with the notable exceptions of Dr. Jeanne Benoit and Special Agent EJ Barrett), and he has admitted to having commitment issues. However, this may have resulted from the ending of his relationship with a woman named Wendy Miller, who he was previously engaged to.
In the Season 1 episode, Dead Man Talking (episode), Tony was attracted to, and even kissed, a pre-operative transsexual who had murdered one of Tony's co-workers which left him stunned, though he recovered quickly.
In the Season 1 episode, Enigma (episode), Tony mentioned that he had once dated a social worker named Michelle who, after he ended their relationship, broke into his apartment and filled his closet with dog crap. He also had a short relationship with NCIS Special Agent Paula Cassidy and once dated his high school music teacher, named Wendy, who he was even engaged to when he started working for NCIS.
Tony also broke up with a Navy lieutenant (who had left her then-fiance for him), and shortly after Tony broke up with her, she posted his name, identity and information on a herpes alert website which as revealed in the Season 3 episode, Frame-Up (episode).
In Hiatus Part 1 (episode), Tony states that he has a better of hooking up with Jessica Alba. This happened in real life as Michael Weatherly who plays Tony was engaged for a time to Alba while the two were on the show, "Dark Angel".
Tony has a friendly relationship with Abby. She has shown the strength of their friendship in such cases as when she did everything possible to find out who the real killer was when her assistant framed him for murder, when he was seemingly blown up and when he returned from his time as an agent afloat.
Abby constantly shows her feelings for Tony, as "I love, and would hate to see you hurt". She can be upset with him at times, such as when someone ate her cupcake, when NCIS director Jennifer Shepard was killed and he and Ziva David weren't where they were supposed to be, but these feelings have resolved and she is back to her own smiley self, which Tony loves. It's often shown that Tony feels as if Abby is a sister he never had, or vice versa. Abby is about as big a movie fan as Tony himself is, and that also solidifies their relationship.
Dr. Jeanne Benoit
In Season 4 Tony's new girlfriend, Jeanne Benoit, was introduced. Tony and Jeanne did not initially consummate their relationship, because Tony revealed that he wanted to "take it slow" out of fear of this relationship becoming like his earlier ones. When questioned by Jeanne, Tony's explanation revolved about his previous misogyny and that a repeat performance would ensue if they followed the same route. Tony and Jeanne subsequently consummate their relationship in the episode Smoked (episode). Tony was determined to have a positive outcome for this relationship and went to great lengths, though often with a lot of inspiration from films, to make their relationship special.
Despite his earlier good intentions for the relationship with Jeanne, Tony couldn't bring himself to tell her that he loved her which caused trouble between them. Tony was told by his earlier love interest, Paula Cassidy, who had just lost two of her agents and blamed herself for their deaths, that if he loved someone, he should tell her while he still could which the team spoke about during Grace Period (episode). Tony was left distraught following the death of Cassidy during a suicide bomb attack on Gibbs's team. He later went to see Jeanne and, following Cassidy's advice, told her he loved her. The last scene of the episode showed Tony embracing Jeanne while crying on her shoulder with REM's Everybody Hurts playing in the background.
Tony showed his commitment to the relationship when he confronted Jeanne about her previous boyfriend. Tony's suspicions became aroused by the constant contact between Jeanne and her former boyfriend in the form of calls and emails. In the Season 4 episode, Friends and Lovers (episode), Tony coincidentally met Jeanne's former partner, who was in fact a Metro police officer named John, though neither of them knew about the other's relationship with Jeanne. They bonded through the fact that they were very similar in character, sharing many habits and traits.
Unbeknownst to either Tony or Jeanne, John said goodbye to Jeanne in an email and died in Tony's arms after being shot by a serial killer the team were tracking.
It was revealed that Jeanne's father was "René Benoit" (aka The Frog), the French arms dealer that NCIS Director Jenny Shepard had been obsessively trying to capture for ten years as she seemingly held him responsible for her father's death.
However, the opening episode of Season Five, Bury Your Dead (episode) revealed that Tony was using Jeanne, as part of an NCIS assignment (with a tie in to the CIA's Operation Lodestone), to infiltrate an arms smuggling network which ended in disaster after Jeanne learned of who Tony really was. After arriving at her apartment, Tony found it completely abandoned and discovered a letter from Jeanne.
In the next episode, Family (episode), Tony was struggling with how his relationship with Jeanne ended and throughout the episode has flashbacks on the relationship. Ziva tried to offer her support to Tony, but he rejected her attempts insisting that he is fine. At the end of this episode the message in Jeanne's card for Tony was revealed: "I am not coming back. You need to choose." After looking at a family reunited with their newborn baby, Tony tossed the card into the fire and joined the team, revealing that he had chosen NCIS over Jeanne.
Jeanne made a reappearance later in the season when she accused Tony of murdering her father in the Season 5 episode, Internal Affairs (episode). At the end of the episode, even though Tony was initially angry with Jeanne for accusing him, Ziva advised him to "be a man" and tell her what she needed to hear. Tony spoke to Jeanne, apologizing for getting her caught in the middle of something that wasn't her fault. Jeanne responded by asking Tony if their relationship was real and, after a pause, he answered "No". Jeanne then told him she wishes she had never met him.
In a conversation with Tara Kole during the Season 6 episode, Knockout (episode), Tony admitted that since his relationship with Jeanne ended he's not been enjoying his normal level of success with women, despite his continued bravado to his co-workers.
The season 8th episode, "Baltimore" revealed that he was engaged to a school teacher named Wendy. She actually was his high school music teacher. She left him the day before their wedding. Years later, Tony found out that Wendy left him because he was "The One" for her and she was not yet ready to meet "The One."
NCIS Special Agent Vivian Blackadder
Both Tony and Viv made their debut appearances in "Ice Queen" where it was clear that they had something of a sibling relationship although Tony was left concerned by Viv's constant need for revenge against the terrorist who had carried out the USS Cole bombing that had killed her brother.
It's presumed that after Viv blew the anti-terror operation, Tony stopped speaking to her and cut off any kind of communication with her for good, possibly because he was angry at her for jeopardizing the operation or putting Gibbs's life in danger or maybe because he felt she was too far gone to be reasoned with.
NCIS Special Agent Caitlin Todd
Tony's relationship with Caitlin Todd was in many ways something of a sibling relationship, but with a constant undertone of flirtation and the possibility of something more. Tony and Todd were in constant competition. Their bickering got so bad that at one point they sought counseling from Ducky during the Season 2 episode, Pop Life (episode). However, on many occasions he was shown being considerate, kind and even borderline romantic to Todd. He bought her flowers as a peace offering after annoying her in the Season 2 episode, Vanished (episode) although Gibbs later revealed that Tony had gotten the number for Kate's favorite florist by going through her PDA, triggering Kate's anger. He even showed concern for her after the episode "Bête Noire" while she struggled to recover from being held hostage by the unnamed terrorist.
In the Season 2 episode, The Bone Yard (episode), Tony had been almost possessive of Todd when McGee posed the idea of pretending to be Todd's partner to get into a paternity clinic to photograph evidence for Abby; saying he would do it instead of McGee. Later in the same episode, he told Todd he thought they made a good couple; to which she replied "Maybe for the Jerry Springer show".
In extras seen on the Season 2 DVD Box Set, the producers stated it was intended for there to be a relationship between these two characters which would have happened had Kate not died in the finale.
In the episode SWAK (episode), after Kate was found uninfected, she continued to stay with Tony, lying about her condition to him even though she knew that the risk of infection was still imminent.
In Twilight (episode), Tony was a witness to Kate's death and having been standing right next to Kate just seconds before she had been murdered after being shot in the head, Tony was hit with some blood from Kate's fatal wound which was revealed to have covered nearly the entire right side of his face.
Like the rest of the team in Kill Ari Part 1 (episode), Tony tried to cope with Kate's death and even imagined Kate talking to him although keeping in terms with Tony's chauvinistic personality, Todd appeared in the Catholic schoolgirl uniform that he had been asking about in the episode, Bikini Wax (episode). After telling him that she always knew what he was thinking, she realized that she was wearing the uniform and quickly berated him, saying "Tony, I just died, and you're having a sexual fantasy?" to which he replied, "Can't help it. Sometimes I used to picture you naked" and she responded by screaming in shock.
Kate's death while leaving the team psychologically scarred and broken had something of a life-changing impact on DiNozzo as although Tony still retained his humorous side, he ultimately "grew up", developing a fierce protective streak towards his NCIS surrogate family/colleagues.
In the Season 9 episode, Life Before His Eyes (episode), it is shown that if Kate hadn't died, in an alternate reality, he and Kate would have eventually gotten married and they would have had a daughter named Kelly.
Ex-Mossad Officer/NCIS Special Agent Ziva David
Tony's relationship with Kate's replacement, Ziva David was almost the same with the two attempting to outdo each other in verbal and physical competitions. Ziva taunts Tony in much the same way Kate did before she was killed. Some aspects of Ziva's personality disturb him, such as the fact that she sleeps with a gun in her hand and snores very loudly, as shown in the Season 3 episode, Under Covers (episode), causing Tony to remark that Ziva sounds like a drunken sailor with emphysema.
During that episode, Tony and Ziva repeatedly faked sexual intercourse to solidify their cover as married assassins. The FBI agents who were monitoring them told McGee that they believed the sex was real, making him wonder what really happened between Tony and Ziva. Also during this episode, Ziva referred to Tony as "My Little Hairy Butt."
In the subsequent episode, 'Frame-Up (episode), Ziva rated Tony's butt a two out of five, telling him, "I took three points off for excessive hair." He replied delightedly, "That's a five!," to which Ziva chuckled and said, "If you shave."
In the Season 4 premiere episode, Shalom (episode), Ziva learnt that Mossad, apparently on her father's orders, had been spying on her for several months; the surveillance revealed that Tony had been visiting Ziva at her apartment at least once a week for the past three months, leading to suggestions that the two have become intimate—or merely that they see each other socially. She neither confirmed nor denied the implication of intimacy in the episode.
In Singled Out (episode), Ziva began questioning Tony about an unidentified girlfriend. Subsequent episodes later established that Tony was building a relationship with medical doctor Jeanne Benoit and no apparent romantic link existed between him and Ziva.
In Driven (episode), it was revealed that Ziva was unaware of Tony's romance with Benoit and had thus been misreading some of his secrecy. Due to Tony's frequent clandestine visits to a hospital (where Jeanne worked) and his claim that he was undergoing tests, Ziva indicated to Gibbs that she was worried that he might be having a medical problem related to his exposure to Y. Pestis from the episode, "SWAK".
In Identity Crisis (episode), Ziva allegedly exhibits jealousy and disappointment of the lack of a relationship between herself and Tony; when she stated that she thought Tony was ready for a "real" woman.
Furthermore, during In the Zone (episode), Ziva got rather frustrated at the idea of Tony sharing a room with a fellow female agent.
In Agent Afloat (episode), Ziva hinted that she missed him whilst he was been serving as an NCIS officer aboard Naval ships, his new rank being "Agent Afloat".
During the episode Nine Lives (episode), Tony showed an interest in Ziva's vacation to Israel despite the fact that she's only just returned. Upon finding a picture of a man on her desk, Tony's interest is stimulated further; not knowing that the man in the picture was Ziva's Mossad partner. Tony also told her to have a good trip (Nisiya Tova) in Hebrew demonstrating either his willingness to attempt to impress her or simply a willingness to learn a phrase in her native language.
Cloak (episode) revealed more about their relationship, though not necessarily evidence of mutual romantic attraction. When placed in a war game, Ziva disobeyed Gibbs's orders not to engage, thereby causing the opponent guardsmen to attack Ziva and Tony. Both NCIS members attempt to aid the other; Tony was knocked unconscious, and Ziva managed to land a few good blows on the guardsmen before being knocked unconscious herself. Later, they shared an angry conversation in the elevator, where Tony accuses Ziva of disobeying Gibbs and provoking the fight. Defending her actions, Ziva reveals that she acted on impulse. They both say that they are "tired of pretending": Tony about the politics in the hunt for the mole within the team, which required the team members to withhold information from each other; Ziva about an undisclosed matter.
Their relationship and partnership faced its greatest challenge in the Season 6/NCIS: Los Angeles pilot episodes, Legend Part 1 (episode) and Legend Part 2 (episode) where Tony suspected Ziva was being less than truthful with him. He later discovered Ziva was in a relationship with Mossad officer Michael Rivkin, an assassin who caused major problems for the NCIS Major Case Response Team and the Office of Special Projects when he targeted the members of a rogue terrorist cell that the agency was after.
To cover his tracks, Rivkin killed the various members, leaving their corpses behind and as such, an angry Tony later confronted Ziva over it with Ziva stating that she would not tell Tony of Rivkin's location if she knew it but she would tell Gibbs.
The penultimate episode, Semper Fidelis (episode), saw Tony and Rivkin met each other in public for the first time. Hours later, at Ziva's apartment, Tony arrived to talk to her, only to discover that Rivkin was there. When Tony attempted to arrest Rivkin for the deaths of the cell's handler and an ICE agent, a massive brawl broke out with both men fighting against one another. The fight came to an end when Tony was forced to shoot Rivkin in self-defense after Rivkin had attempted to stab Tony with some glass.
Ducky's tests later determined that Rivkin had been drunk at the time of the fight which also explained how Tony was able to get the better of Rivkin despite Rivkin having been Mossad.
Ziva later furiously confronted Tony over his involvement in Rivkin's death during the Season 6 finale episode, Aliyah (episode) and she later told Gibbs that it had become apparent that she and Tony could no longer work together. Gibbs responded by leaving Ziva behind in Israel. Ziva later rejoined Mossad, working for her father once again.
In the last few seconds of the episode, Tony was shown to be considering calling her, but resigned himself to the fact that she is gone and "will call when she's ready", only for the closing scene to show that Ziva had been taken prisoner in North Africa and tortured by Saleem Ulman, a terrorist demanding information on NCIS.
In the premiere of Season Seven, Truth or Consequences (episode), Tony having been captured by Saleem and his men was later given a truth serum while being held captive in Somalia. It was later revealed that Ziva was actually alive, not as the team had originally suspected. When Ziva asked what Tony was doing here, Tony told her that he couldn't live without her.
In Reunion (episode), Tony and Ziva spoke in the men's restroom about the events involving Michael. Ziva confessed that she was grateful that he has always "had her back." Before she left the restroom, Ziva kissed Tony on the cheek, saying that his "instincts were right".
In Jet Lag (episode), Tony and Ziva, on a mission to protect a key witness, were stuck together in one hotel room in Paris. On the return flight, the witness Nora Williams asked Ziva and Tony whether they are together, or why wouldn't they be, etc. They dodged those questions, and when Nora found out they shared a hotel room, Ziva told her that she took the couch. However, upon their return to D.C., McGee asked Tony where he slept, and Tony told him that he slept on the couch. Ziva then looked at Tony after McGee had left and asked him why he lied. Tony in response asked her why she lied to Nora. Also, Tony told her that his favorite picture of Paris is the only one with a person in it. When he gave Ziva the picture, the audience saw that the person in the picture was Ziva.
Later on in the episode, Obsession (episode), Tony described the type of women he was looking for, and ended up describing Ziva, though it is unclear if either of them realized it.
Tony has also demonstrated interest in any perceived attention both of his female partners — Caitlin Todd and Ziva David — receive from men. In Ziva's case, this is particularly true of NCIS Field Agent Chad Dunham and former Marine Corporal Damon Werth yet no reason has been given for this attitude.
He is also shown to look annoyed (or possibly jealous) when his father flirted with Ziva. When DiNozzo Sr. asked him when he was going to come to his senses and sweep Ziva off her feet, his expression is never really shown but he might have been embarrassed.
In the Season 9 episode, Housekeeping (episode), Tony was advised by a former flame to pursue a relationship with Ziva. At the end of the episode, they talked, but before it could get any further, Ziva was called by her then far-away boyfriend Ray.
In the next episode, A Desperate Man (episode), Ziva is avoiding Ray and tells Tony off for talking to him. Later on, she confides in him about the reason why and he comforts her before they get interrupted by their suspect. After the proposal, Tony displays interest and he discusses about when he got engaged. In the last scene, he helps her with her phone before the victim's husband comes to fight them. As they leave, Burris asked how long they've been together but they simply laugh it off and claim that they are just co-workers and good friends. Burris tells them to cherish that and the last foof is of them in the elevator, smiling at each other.
In the Season 9 finale episode, Till Death Do Us Part (episode) the two have a rant about weddings and stare at each other at the end. When Tony wonders what he'd do if he had to deal with that, Ziva suggests eloping and they share a look before Gibbs enters.
Not long later, when they're both evacuating the building and making sure all the NCIS employees will leave due to the bomb threat, Tony tells his partner to go but she grabs his arm, saying that she "won't go without him" and leads him down a corridor.
In the last few minutes, they are seen in the elevator as the bomb hits. She jumps into his arms and they fall down, his arm around her waist and them holding hands. This can be seen as them wanting to protect each other.
In Extreme Prejudice (episode), Tony and Ziva are eventually freed and rescued from the elevator but months later, in Shabbat Shalom (episode) and Shiva (episode), things take a turn for the worse when Eli, Ziva's estranged father and Jackie Vance, Vance's wife are murdered by an assassin who later kills himself.
From that moment on, Ziva becomes obsessed with avenging her father by any means necessary, ignoring the team's efforts to help her.
She later discovers that a colleague of her father, Ilan Bodnar was the one who arranged the killings of Eli and Jackie and as such, embarks on a quest to find Bodnar which secretly continues with her even going so far as to enlist McGee's help which DiNozzo later discovers during Chasing Ghosts (episode).
The search eventually takes DiNozzo and Ziva to Berlin where at the end of Berlin (episode), they are involved in a car accident that leaves both of them injured but despite being in pain, Ziva is not deterred and instead continues on, eventually discovering that Bodnar is planning on leaving for South Africa in Revenge (episode). She then heads to the port and sneaks onto the ship where the two meet each other and instantly engage in hand-to-hand combat which ends when Ziva throws Bodnar off a platform and onto some boxes, killing him instantly just as Gibbs, DiNozzo and McGee arrive.
In the last few seconds of the episode, Ziva, bruised arrives at the office to tell Vance that it's over.
Unfortunately, the Bodnar situation draws the attention of Department of Defense agent Richard Parsons who begins investigating the team in Double Blind (episode). Realizing that Gibbs is in danger, Ziva along with DiNozzo and McGee resign from their positions as NCIS agents in the Season 10 finale episode, Damned If You Do (episode) with McGee telling Vance, "Gibbs would do the same for us".
In the Season 11 premiere episode, Whiskey Tango Foxtrot (episode), after learning that Ziva has gone into hiding due to the fact that she and her former NCIS colleagues are now being targeted by a milita group called the "Brotherhood of Doubt", Tony is later seen glancing at a photo of Ziva and Ari and wondering where Ziva is.
In Past, Present and Future (episode), Tony finds Ziva in Israel and after the two have their first kiss, Ziva chooses to stay behind in Israel despite Tony trying to get her to return to the United States.
As a result of Ziva's departure, Tony later develops insomnia during Once a Crook (episode) although he is seen sleeping peacefully for the first time in the last few seconds of the episode.
NCIS Special Agent Erica Jane Barrett
In Season Eight, Tony meets Erica Jane Barrett, who is revealed to have been given the position he was originally offered as team leader in Rota, Spain. They show apparent romantic interest in each other upon meeting. This ultimately blossoms into a relationship in the Season 8 episode, One Last Score (episode), when Tony talks to EJ while she is showering. She ultimately emerges after he hands her a towel, and answers Tony's assertion that there were rules against the two dating (Gibbs's rules) with "No, there aren't."
In later episodes, Tony appears to have a considerably strong desire to maintain this relationship, defying Gibbs, which rarely happens. Tony's desire to stay with her also appears to be uncharacteristic, as he normally avoids relationships that get too serious. He also says to Ziva in confidence in Two-Faced (episode) that "I understand her [E.J.]. That's why we work so well." In the same episode, she talks about how home is "all about the people around you," while smiling at and holding Tony.
After the Port-to-Port killer attacks her team, resulting in one of her agents being shot dead, and the other being left critically injured, EJ is tortured and nearly killed but manages to survive. She stays in D.C. for a short time with Tony, before disappearing on a sabbatical. When she reappears, in the Season 9 premiere episode, Nature of the Beast (episode), she is en route to tropical islands when Tony finds and stops her, convincing her to return to D.C. again. While in D.C. she is shot and apparently killed, disappearing again.
Tony is unable to locate her, and after several months, moves on, believing her to be dead. However, she reappears again in "Housekeeping", still being stalked by a serial killer. Tony is shown to have conflicting feelings towards her when she reappears, feeling hostility because she left him, believing him to be dead, during the ambush she disappeared in. However, he still feels his old romantic attraction for her, though he is bitter about her frequent disappearances, stating that "I've noticed you have a habit of disappearing. Consequently, I spend a lot of time looking for you. A lot... of time..." Eventually, after they capture the man who was attempting to kill her, E.J. is able to stop running.
Despite this, she chooses to return home, to where her parents live in D.C. She and Tony indirectly talk about their future, but E.J. ultimately chooses not to resume their old relationship, saying, "Tony... we've been down this yellow brick road before." She then kisses Tony and the two part as friends as she takes a vacation from NCIS. Her parting advice to Tony is to seek a relationship with Ziva, saying that "She cares about you."
NCIS Director Jenny Shepard
In Season Four, Tony's relationship with Jennifer Shepard was shown to have warmed considerably in comparison to the end of the third season, with Tony occasionally being caught referring to her by her first name with even Gibbs joking about how close they were. The main reason for the warming of their relationship is the fact that Tony was involved in an ongoing operation run by Shepard, which was of personal importance to her. As they are keeping secrets, they began developing a strong level of trust.
Upon Gibbs's absence Tony took on his job and its associated responsibilities; this meant his interactions with the director became more frequent and as a consequence his relationship with her became more familiar, as seen in the episode Shalom.
Despite Gibbs returning, Tony stepped down as team leader while also secretly assisting Jenny with her operation.
In the Season 5 premiere episode, Bury Your Dead (episode). as a result of the undercover operation being blown, Tony and Jenny's relationship cooled and although they were still on friendly terms, the past friendship they had in the past presumably disappeared, presumably due to Tony's loyalty to Gibbs and Jenny's overall refusal to accept any blame for the operation which had been her idea.
In the last few seconds of the Season 5 finale episode, Judgment Day Part 1 (episode), Tony, after having been called over by Ziva discovered Jenny's body in the corner. He then knelt down, feeling for a pulse but found none, causing him to take a sharp breath and close his eyes in dismay before answering Jenny's ringing cell-phone. It could be presumed that he was the one who told Gibbs of Jenny's death.
He considered the event to be his fault because he had followed the director's instruction to abandon her protection detail and was later seen in the morgue, drinking as a possible means of helping him cope.
In the Season 6 episode, Agent Afloat (episode), Ziva reveals that, in the aftermath of Jenny's death, Tony had been drinking out of guilt.
Special Agent in Charge Leroy Jethro Gibbs
Tony first encountered Gibbs while working as Detective for the Baltimore Police Department, when Tony arrested Gibbs on suspicion of having committed a crime. At the time of the arrest, though, Gibbs broke cover and revealed his true identity to DiNozzo, Tony was credulous and did not believe Gibbs. Tony greatly respects Leroy Jethro Gibbs and claims to have a father/son type relationship with him. Tony is easily riled when it seems that Gibbs has a new favorite, and tries desperately to win back favor. Gibbs has the tendency to smack Tony on the back of the head whenever he says or does something inappropriate. However, during the Season 1 episode, Missing (episode), Gibbs told Tony that he was "irreplaceable".
In the Season 1 finale episode, Reveille (episode), it's revealed that Tony tolerates being smacked only by Gibbs and reacts angrily when Kate Todd gives him a similar smack and the same reaction is shown when Ziva mirrors Gibbs's smack during the Season 3 episode, Probie (episode).
Tony prides himself on knowing many of the military terms, acronyms and slang Gibbs regularly uses which sometimes confuse civilians. Phrases such as these uttered by Tony include "On your six" or "got your six". This refers to the six o'clock position being at the back as 12 o'clock is at the front, as in ground or flying formations. Throughout the first seasons of the series Tony made it a point to explain several agency acronyms to Todd and occasionally to McGee.
In the Season 3 premiere episode, Kill Ari Part 1 (episode), Gibbs starts "being nice" for about half the episode. The change in his demeanor bothers Tony, and he tells McGee: "He's not Gibbs if he's nice." Tony then tries to tick Gibbs off so that he will return to the way he previously was; upon his success at making an inappropriate comment towards the Director (at which Gibbs slaps him in his typical way), he welcomes Gibbs back, pleased.
After Gibbs left at the end of season 3, Tony took his place as team leader. As leader, he tried to emulate Gibbs' leadership style, but he did make some changes. These included calling "Campfire" discussions (an impromptu sharing of current information among his fellow agents, which his peers found annoying), and reorganizing the equipment in the field truck. When Tony is offered his own team in Rota, Spain, he turns the offer down claiming that he wanted to keep an eye on Gibbs, whose memory has still not completely returned after the blast at the end of season 3. Gibbs indicates his belief that Tony is ready for his own team, unaware of the fact that Tony has already been offered this opportunity.
During the time Gibbs was away, Tony began working on an undercover operation with Director Shepard. Gibbs, unaware of the operation and noticing an unusual closeness between Tony and the director, questions the relationship. When the undercover operation was finally revealed to Gibbs, Tony apologized for not disclosing any information about the operation.
In Flesh and Blood (episode), Gibbs tells Tony's father that Tony is the best young Agent he's ever worked with.
Special Agent Timothy McGee
Tony's relationship with Timothy McGee was initially problematic, like one between a teasing older brother and a shy younger brother. Part of this could be considered hazing, as McGee is the least experienced member of the NCIS team and ranks only as a junior field agent having only worked at NCIS for five or six years while Tony has worked at NCIS for nearly ten years, having presumably joined the team in 2001.
For example, when McGee joined the team as a probationary Special Agent, Tony began calling him "Probie" (including versions of "Probie", such as "Probie-Wan Kenobi", "Probie Pan", and "Probie-san").
Some of Tony's other nicknames for McGee are plays on his name such as "McGeek" and "McGoogle". He even calls him "McProbie", a combination nickname. He also refers to McGee's online-gaming persona Elf-Lord, though Gibbs is the one that usually calls him that. In some cases the names refer to aspects of McGee's character, such as "McTardy", a reference to McGee being late, and "McCheat", a reference to McGee supposedly cheating at Scrabble. Often, DiNozzo and Ziva David are shown teaming up to tease McGee, although it remains friendly.
Contrary to appearances, Tony values his relationship with McGee, as seen in the episode "Probie" where Tony goes out of his way to support McGee and makes an effort to cheer him up. Particularly shown when McGee accidentally shoots an undercover police officer, Tony is the first one to try and allay McGee's feelings of guilt.
At one point, after McGee has expressed his chagrin at being called "Probie", Gibbs tells him that his first senior agent still calls him "Probie" and suggests that it is not a sign of distaste or disrespect.
During Gibbs's absence however, McGee becomes the senior field agent as Tony is now team leader. At this time, Tony shows much more respect for McGee and confidence in his abilities.
In the beginning of the seventh season Tony has more frequently called McGee by his first name, Tim, instead of these nicknames. An example of this is when McGee is explaining something to Gibbs and Tony says, "It's a burn phone, Tim, just say burn phone."
It has been shown a few other times as well that the relationship between the two agents is on a much more equal footing as the show moves into the seventh season.
McGee is very rarely (if at all) referred to as "Probie" anymore by Tony, especially since Ziva has become the probationary field agent on the MCRT although Tony has occasionally called McGee "Probie" in some episodes of season 8, 9 and even 10 but McGee shows no hostility towards the nickname.