"Four years? I'll do it in three."
- - James T. Kirk to Christopher Pike, 2255
James Tiberius Kirk was a 23rd century Human Federation Starfleet officer. As a Starfleet cadet, he was instrumental in the defeat and death of Nero, a Romulan bent on the obliteration of the United Federation of Planets. As a result, he was commissioned directly to the rank of captain and appointed as commanding officer of the service's flagship, the USS Enterprise. (Star Trek)
James T. Kirk was the son of Starfleet officer George Kirk, first officer of the USS Kelvin and his wife Winona Kirk. He was born aboard the Kelvin's medical shuttle no. 37, in the midst of an unprovoked attack on the Kelvin by the Narada, a 24th century Romulan mining vessel commanded by Nero. Winona had been evacuated from the severely-crippled Kelvin along with the rest of the crew and gave birth to James while George Kirk died piloting the Kelvin into the Narada in a kamikaze attack. He was named James Tiberius after Winona's father and George's father, respectively.
Kirk was raised in Iowa, in Midwestern North America, on Earth. His mother remarried. As a young boy, Kirk had a somewhat rebellious streak in him as he once, for example, stole his stepfather's '65 Chevy Corvette convertible, drove it recklessly, got into a high speed chase with local police, then nearly died when he barely managed to jump out, as he drove it into a quarry. As he grew up he had little sense of purpose and by 2255, he was an aimless rebel who had found himself on the wrong side of the law on more than one occasion.
While visiting a bar near the Riverside Shipyard, an inebriated Kirk met and began flirting with a Starfleet cadet named Nyota Uhura. Although annoyed by Kirk's advances, Uhura was surprised that Kirk knew what was involved in the study of xenolinguistics. Moments later, Kirk engaged in a bar fight with three male cadets who were irritated at his cocky attitude and the attention he was giving Uhura. He was ultimately overwhelmed by the cadets until Captain Christopher Pike broke up the fight. Pike, who wrote his dissertation on the USS Kelvin and was familiar with Kirk's story pushed the young man to challenge himself and reach the greater potential he was capable of achieving, calling him "the only genius level repeat offender in the Midwest".
Pike tried to persuade him to join Starfleet, firmly believing that he could do more with himself than get into bar fights and break all the laws in the state of Iowa. Kirk laughed at the idea of joining Starfleet, but Pike reassured him that with his "off-the-chart" aptitude he could make captain and have his own ship in only eight years. He reminded him that his father had saved eight-hundred lives, including Kirk's and his mother's, and dared young Kirk to do better.
Soon after their conversation, and to the surprise of Pike, Kirk decided to enlist with the intent of completing the Academy training in three years. He rode onto the shipyard, gave his bike to a construction worker, and boarded a shuttle for new recruits heading to Starfleet Academy. It was on his trip to the Academy where he first met and befriended Doctor Leonard McCoy.
Kirk and McCoy became close friends at the Academy, though Kirk frequently exasperated McCoy with his maverick nature. Kirk had an eye for attractive female cadets and he once ended up in the dormitory of an Orion female cadet named Gaila. He was caught and hid under the bed when her roommate, Cadet Uhura, arrived unexpectedly. On discovering him, she angrily threw him out.
It was at the Academy that Kirk also met Commander Spock. Kirk had failed the Kobayashi Maru examination twice but decided to take it a third time, being sure that he would succeed. He eventually managed to cheat the test and won. Spock, who programmed the "no-win scenario," investigated the matter.
While discussing his cheating ways with his superiors, Kirk argued that the test itself was a cheat, and stated that he didn't believe in the no-win scenario. Kirk asked to face his accuser, and Spock stepped up. This was the first time the two met and clashed over their differences.
Kirk and Spock continued to engage in a heated argument (the accused becoming particularly agitated when Spock suggested that, "of all people", George Kirk's son should recognize the no-win scenario), when the hearing was suddenly interrupted after Starfleet had found out that Vulcan was under attack by Nero.
Many of the cadets were called into action after the news but Kirk - who had been suspended because of his recent academic dishonesty charges - was not allowed to join. McCoy, however, was able to get him aboard the Enterprise by injecting him with a vaccine that temporarily rendered him sick so he could be transfered to the ship on medical grounds.
Kirk tried telling Captain Pike and Spock about Nero's attack and his trap and with the help of McCoy and Uhura he was able to convince Pike about the trap. Pike raised the Enterprise's shields as they entered the Vulcan system, only to find a massive debris field of destroyed Federation starships having been attacked by Nero.
Along with Chief Engineer Olson and Lieutenant Hikaru Sulu, Kirk skydived onto the platform. Facing off against two of Nero's crew, Kirk and Sulu eventually killed both of their adversaries before destroying the platform, but not in time to prevent Nero from successfully completing his plan to destroy the planet Vulcan.
After returning to the Enterprise, Kirk attempted to dissuade Commander Spock from a rendezvous with the rest of Starfleet at the Laurentian system. He urged him to go after the Narada as the ship left for Earth rather than waste time trying to gather additional forces in the opposite direction, but Spock was relentless. When Kirk became more and more heated in his objections, Spock finally ordered Kirk's removal from the bridge, knocked him out and threw him off the ship in an escape pod.
Marooned on Delta Vega
Kirk landed on Delta Vega, some kilometers away from a Starfleet outpost. Despite an inhospitable environment, he left his shuttle and soon was chased into a cave by a predatory creature. Just as he was about to be eaten, the creature was was scared off by an elderly Vulcan man, who revealed himself to be Spock from a future time, which Kirk dismissed as "bullshit" – but changed his mind when the old man mentioned Nero. Spock revealed to Kirk through a mind meld Nero's intentions, also telling him that in his timeline, Kirk was the captain of the Enterprise. Understanding that their only hope was to have the Enterprise pursue the Narada instead of returning to the fleet, they realized that they had to get the other Spock to step down from command. Fortunately, while the Enterprise had long since left the system, Spock was aware that one of the officers at the nearby outpost was Montgomery Scott, who in his universe had devised a way to transport onto a ship at warp speeds. Giving Scotty his own equations a century ahead of schedule, before beaming the pair onto the Enterprise, Spock advised Kirk to elicit an emotional reaction from the young Spock so that everyone could see that he was emotionally compromised and not fit for command, stating that the only way to defeat Nero was for Kirk to take command of the ship himself.
Following the advice of Ambassador Spock, Kirk goaded Spock with assertions that Spock cared nothing for what had happened to Vulcan or the death of his mother, whom he accused Spock of never having loved. The last remark did the job and Spock violently attacked Kirk before Spock's father stepped in and stopped him. Spock immediately relinquished command. Kirk, as acting first officer, took command and ordered pursuit course of the Narada to Earth.
Spock, deferring to Kirk as captain and both successfully beamed onto the Narada. After an intense firefight in which they killed several Romulans, they made it to the elder Spock's ship; upon being identified as its pilot, Spock quickly realized exactly who Kirk's unknown benefactor had been. Leaving Spock to secure the ship, Kirk went to retrieve Captain Pike. In searching for the captain he encountered Nero and his first officer Ayel; the pair easily overpowered him, but when Nero, after boasting that he would kill Kirk just like his father, discovered that Spock had destroyed the drill, he furiously returned to the bridge. Initially, Kirk was no match for Ayel either, but the overconfident Romulan was too busy mocking his "weak" victim to notice the theft of his disruptor, and offered the chance to speak, Kirk's "last words" were "I got your gun!". After retrieving Pike – who repaid his defenseless savior by grabbing the stolen disruptor and gunning down two Romulans walking in on the escape – and against Spock's advice once again, Kirk decided to give Nero and his remaining crew a chance to beam to the Enterprise and surrender. After Nero strongly declined, Kirk easily decided to have all weapons fired and the Narada destroyed.
Captain of the USS Enterprise
Upon his return to Earth, Kirk was commended and officially appointed as Captain of the Enterprise by Admiral Richard Barnett for his actions, which demonstrated his ability as an extremely able commanding officer fully capable of leading a Federation starship crew in the most dire of situations.
Dressed in his new captain's uniform, Kirk took command of the Enterprise. Commander Spock arrived and requested the permanent post as Kirk's first officer, which Kirk was honored to accept.
Kirk initially had a largely antagonistic relationship with Spock, mainly due to their vastly different philosophies and approaches to command. The frictions began first at Starfleet Academy when Kirk cheated on the Kobayashi Maru test Spock had designed, and then later continued when the disparate pair worked side by side on the USS Enterprise and Kirk was put in charge as second in command by Captain Pike. Tensions between the two culminated in Spock throwing Kirk off the ship altogether. However, their attitudes towards each other softened after an encounter with an older version of Spock from an alternate future, who revealed that in fact the two had shared a great friendship in his timeline. After Kirk goaded Spock into revealing his emotional instability, Spock defered to Kirk's command and the two worked as a team to stop Nero and rescue Pike. After learning how important their friendship was from Spock Prime, Spock offered to be Kirk's first officer which he happily accepted.
Kirk and McCoy met on a transport shuttle to Starfleet Academy. The pair found themselves in adjacent seats where a slightly neurotic McCoy instantly opened up to the rebellious and somewhat incredulous Kirk. The two remained good friends throughout their time together at the Academy. When the time came, McCoy always had Kirk's back, such as helping him get aboard the Enterprise after his suspension and berating Spock for throwing Kirk off the ship and marooning him on Delta Vega.
Kirk first met Nyota Uhura at a bar in Iowa in 2255, audaciously flirting with her while intoxicated, angering some other Starfleet cadet patrons of the bar, resulting in a fight. He met her again when the two studied at Starfleet Academy, although she preferred to keep a distance from him - not even ever telling him her first name - as she saw him as brash and uncouth. The pair ended up serving together aboard the Enterprise, but she continued to maintain her distance from him. It was Kirk and his need for a xenolinguist that got her stationed on the bridge. When Kirk was granted permanent command of the Enterprise, he chose Uhura as one of his senior officers.
- 2233: Born on Medical shuttle 37 that was attached to the late USS Kelvin
- 2233-2255: Raised in Iowa
- 2255-2258: Cadet/Lieutenant at Starfleet Academy
- Appointed acting first officer of the USS Enterprise
- Elevated to acting captain of the USS Enterprise
- Appointed captain of the USS Enterprise
"Citizen, what is your name?"
"My name is James Tiberius Kirk!"
- - Iowa cop and a young Kirk (Star Trek)
"If you don't give me a name, I'm gonna have to make one up."
"Uhura? No way! That's the name I was gonna make up for you!"
- - James Kirk and Nyota Uhura (Star Trek)
"I'm impressed. For a moment there, I thought you were just a dumb hick who only had sex with farm animals."
"Well, not only..."
- - Nyota Uhura and James Kirk (Star Trek)
"Do you like being the only genius-level repeat offender in the Midwest?"
"Maybe I love it."
- - Captain Pike and Kirk (Star Trek)
"Two Klingon vessels have entered the Neutral zone and are locking weapons on us."
"Yeah, don't worry about it."
"I don't believe in no-win scenarios."
- - Kirk (Star Trek)
"Who was that pointy-eared bastard anyway?"
"I don't know. But I like him."
- - Kirk and McCoy, after meeting Spock for the first time (Star Trek)
"I am Spock."
- - Spock Prime and James Kirk (Star Trek)
"What're you doin' here?"
"Just following orders."
- - Captains Pike and Kirk, as the latter (recalling an order to "come and get me") rescues the former
"I would rather suffer the end of Romulus a thousand times. I would rather die in agony, than accept assistance from you."
"You got it. Arm phasers, fire everything we've got."
- - Kirk's response to Nero, after suggesting Nero to surrender peacefully (Star Trek)
"Bones... buckle up!"
- - James Kirk to Leonard McCoy, as his first words on the bridge of the Enterprise as its assigned captain (Star Trek)
James T. Kirk was portrayed by Chris Pine. Younger versions were portrayed by Jimmy Bennett and an infant performer. For the scene in which Kirk is running into a cave on Delta Vega, child actor Joshua Greene served as body double for Pine. The producers did this to let the entrance of the cave look bigger.
Originally, Winona would not have remarried, but left her boys to be cared for by her brother (or brother-in-law) Frank (Brad William Henke), who was abusive to them whenever she was off-world. This forced George Samuel Kirk to run away from home, and Jim, who was a good pupil who always obeyed orders, to steal George's antique car that Frank treated as if it was his own.
The novelization of 2009's Star Trek by Alan Dean Foster states that Winona Kirk was given an inhibitor that would help slow the birth of James until the Kelvin's return to Earth. However, the impacts to the ship by the Narada's attack cause her to go into early labor. Screenwriter Roberto Orci joked in a message board post that the radiation from Kirk's premature birth in space caused his eyes to go blue.  The prime Kirk has hazel eyes. The novelization also merges the conflicting abusive-adult characters, making "Frank" the boys' step-father, and revealing that he wanted the car washed because he planned to sell it behind Winona's back, which is what truly drives Jim to steal it.
One influence on which Orci and Kurtzman based Kirk and Spock's relationship was the friendship between Paul McCartney and John Lennon, two very different musicians who bonded early in life, partly because they both suffered through the loss of a parent (in Kirk's case, his father, and in Spock's, his mother).