George Kirk was a Human Starfleet officer in the early 23rd century. He was noted for saving the lives of eight hundred people while briefly serving, for merely twelve minutes, as commanding officer of the USS Kelvin during an attack by the Narada. Kirk was also the son of Tiberius Kirk, the husband of Winona Kirk, and the father of James T. Kirk.
When Kirk was a kid, he owned a PX70 motorcycle. According to his son, Kirk often put Winona on the back of the vehicle and it drove her nuts.
Kirk went on to join Starfleet as he truly believed in the humanitarian and exploratory ideals of the Federation. (Star Trek Beyond)
Service and sacrifice
In 2233, at the age of twenty-nine, Lieutenant Commander George Kirk was serving as first officer aboard the USS Kelvin under Captain Richard Robau when it was diverted by Starfleet to investigate a mysterious singularity. (Star Trek, Star Trek Beyond) The Romulan ship Narada, under the command of Captain Nero, emerged through the black hole from the year 2387 and began firing upon the Kelvin, severely damaging the ship.
When Robau departed the Kelvin to negotiate a cease fire, he left Kirk in command of the ship, telling him to prepare to evacuate the Kelvin and set the ship on autopilot. However, it became apparent, when the Narada resumed firing, that its crew never had any intention of negotiating a cease fire. Kirk followed the instructions Robau had given him and gave the order to abandon ship.
Among those being evacuated was Kirk's wife, Winona, who was aboard the ship and was going into labor with their son. Kirk promised to join her shortly thereafter. Attempts to set the ship on autopilot failed, however, and Kirk was forced to remain on board to prevent the Narada from destroying the evacuation shuttles.
He set the Kelvin on a collision course with the Narada. As the Starfleet vessel charged on its suicide course, George used the ship's weapons to shoot down the Narada's missiles before they could impact the fleeing shuttles and escape pods, saving further lives in the process (including those aboard the shuttle containing his wife).
In his final moments, Kirk contacted Winona as she gave birth to their son. They tried to think of a name for their child and he suggested naming the baby after Winona's father, James, rather than his own father. The last thing George Kirk heard before dying in the collision with the Narada were the cries of his newborn son, James T. Kirk. George's sacrifice not only saved the lives of eight hundred people but also disabled the enemy ship.
Captain Christopher Pike wrote his dissertation on the Kelvin and George Kirk. Pike came to admire Kirk, describing him as a man who had not believed in "no-win scenarios" and as someone who had had the instinct to leap without looking, a trait that Pike felt Starfleet had lost by the 2250s.
Because George died prematurely, James T. Kirk never knew his father and thus never had an inspiration to join Starfleet. Instead, he spent his early years as a rebel and trouble-maker until he encountered Pike in 2255. In this encounter, Pike spoke highly of George and told James Kirk that his father had saved eight hundred lives in the twelve minutes he commanded a starship.
Pike dared the young Kirk to do better, a dare that James Kirk responded to by enlisting in Starfleet the next day. In 2258, he fulfilled this dare when he became acting captain of the USS Enterprise and saved Earth as well as billions of lives from Nero, the same man George Kirk had lost his life fighting. Pike reflected to James that George would be proud of his actions when they resulted in James being promoted to the rank of captain and being given permanent command of the Enterprise. (Star Trek)
In 2263, two days before James' thirtieth birthday, Leonard McCoy and James Kirk shared a drink together, remembering George Kirk. During the conversation, McCoy mentioned that James Kirk had spent much of his time trying to be like his father. James was also bothered by the fact that he would now forever be older than George. (Star Trek Beyond)
George Kirk was played by Chris Hemsworth.
In the script of Star Trek, George Kirk was referred to as being thirty-two years old at the time of his death and he was further described as having an "all-American face."  On the other hand, James Kirk muses in Star Trek Beyond that, upon reaching thirty, he'll be a year older than his father when he died, making George twenty-nine at the beginning of 2233, with a corresponding birth year of 2203 or 2204.
As director of the film Star Trek, J.J. Abrams specifically asked for Chris Hemsworth to portray George Kirk, though the actor had only begun working in America a few months beforehand. He received notification of the role one day after he returned to Los Angeles following a couple of months of filming in Chicago. "I had a phone call from my manager saying that I needed to drive across right away to Paramount Studios and meet J.J. Abrams in his office to do the scene," Hemsworth explained. "I cancelled what I was doing, drove over there, did the scene in his office at his desk and he said, 'Fantastic – we have to work together. You start next week.' And that was it!" Although Abrams didn't share much information with the performer at that time, Hemsworth did use a genuine scene from the movie for his audition. He had very little time to prepare for the role, though there wasn't a lot he could do to ready himself for the part anyway. (Star Trek Magazine issue 145, p. 91)
Since this character had never appeared before, J.J. Abrams and Chris Hemsworth were free to collaborate on the portrayal of George Kirk. "On set we discussed how we wanted to play it," remembered Hemsworth. "J.J. had very specific ideas about what we wanted to achieve, but he's also the kind of director that gives you the freedom to try other things and put your own interpretation on it. It was more a case of taking the scenes that we had, and finding the truth in what was being said, then just playing that and trusting in the overall picture J.J. was creating and that the writers had done for us." (Star Trek Magazine issue 145, p. 91)
Constructing a backstory for his own character, Chris Hemsworth came to the opinion that George Kirk is "someone who has quite a strong sense of justice. He's that old-fashioned kind of good guy: he has strong morals and puts other people before himself. But he was also played as someone in his mid-20s. He's still quite young, so I think a lot of who he is was ingrained, maybe through his upbringing. I feel like he had a pretty strong sense of character, and especially to be put in the position he is at such a young age says a lot about who he is." (Star Trek Magazine issue 145, pp. 91-92)
In many ways, Chris Hemsworth was relieved that, because there wasn't much rehearsal time, he didn't have long to consider what he was letting himself in for by playing James Kirk's father. "That was funny," he remarked. "In a really good way, I was thankful for not having enough time to think about it, because the turnaround from the audition to when I was shooting was so quick. I didn't have too much time to think about the pressure that was built around it. But afterward, the more I heard about it, I started hoping I did an okay job! [....] There were a couple of times when I was sitting there on set, and I thought that it doesn't get any bigger than this, in terms of money, expertise and everything that's put into making a film. And I wondered what I was doing there! But [...] it was mind-blowing and exciting." Also, Hemsworth found his confidence regarding his performance was boosted by J.J. Abrams. (Star Trek Magazine issue 145, p. 92)
George Kirk's fate was drastically changed in post-production. As depicted in the original cut of the film, he managed to abandon the Kelvin. It was J.J. Abrams who decided the character would instead defend the fleeing shuttles by piloting the Kelvin on a suicide run into the Narada. Abrams thought George Kirk's sacrifice would make the scene more dramatic but, of course, the revision called for more effects work than had originally been planned. Filming the character's death scene involved a physical effects rig on the set of the Kelvin's bridge, putting the command chair on a slide. "Chris Hemsworth sat in the chair, we slid him forward through the set, and J.J. captured pieces of the performance," recalled Special Effects Supervisor Burt Dalton. "When they put those pieces together in post, it looked as if Kirk was being slammed toward the front of the ship." (Cinefex, No. 118, pp. 48, 51 & 54)
Although Spock refers to George Kirk as having been a lieutenant when he was killed, Kirk is actually shown wearing the rank braids of a lieutenant commander. Lieutenant commanders are usually afforded the privilege of being referred to, in short, as commanders and not as lieutenants; Deanna Troi, Geordi La Forge, and Shelby have also been addressed as lieutenants despite clearly holding the rank of lieutenant commander (in "Encounter at Farpoint", "The Most Toys", "Hero Worship" and "The Best of Both Worlds, Part II", respectively). On the other hand, Starfleet rank insignia has changed over time (for example, no stripes on uniforms in pilot episode "The Cage" but stripes throughout the rest of Star Trek: The Original Series) and sometimes first officers have been portrayed wearing higher ranks than their commission, such as Spock wearing a commander's rank stripes in TOS Season 1 despite meanwhile being a lieutenant commander.
George Kirk may have a brother, since James T. Kirk said he was staying at his uncle's farm in Star Trek Generations. It was never made clear which of his parents had a sibling, though, or if he was just using the term for a long-time family friend. In the film Star Trek, an uncle Frank was cut from the script and reworked into Winona's new husband heard in the film.
Intel's Star Trek tie-in website gave his serial number as SA-733-9624-AM.
IDW Publishing's comic book "Keenser's Story" depicts him as being present for first contact with the Roylans (β), Keenser's people. After Keenser helps them fix their shuttle, George befriends Keenser on the ride back to the Kelvin, Keenser having chosen to go with him with the intention of signing up for Starfleet Academy.