For characters who debuted in Star Trek: The Original Series, see Characters.Star Trek The Original Series
- Obstructive Bureaucrat: Granted, the situation around the Genesis Planet was undoubtedly a very difficult one from a political standpoint, but he point-blank refuses to help Kirk out in any way after being asked to help retrieve Spock's body. On the other hand, he at least seems genuinely concerned for Kirk, rather than just being obstructive for the sake of it.
- Unwitting Instigator of Doom: Played with — had he let Kirk and crew borrow the Excelsior or another starship that was in working order, then the whole fiasco with the Enterprise theft would never have happened. However, without Kirk and crew being in exile on Vulcan at the start of the next film (and not having access to the Klingon Bird-of-Prey), it's likely that the events of that film would have turned out far worse for everyone involved.
- What Happened to the Mouse?: After rejecting Kirk's request to take the Enterprise to Genesis, he's never seen again (and is, in fact, replaced by Admiral Cartwright). Source material suggests that he resigned over what happened.
- Jerkass: Perennially berating Saavik and David for wanting to do their jobs and observe the Genesis Planet because he thinks its too risky. Not out of any concern for Saavik and David, but for his own career.
- Named by the Adaptation: The film only provides his initials, J.T., rather than his actual first name. Supplemental materials reveal the J stands for Jonathan.
- Obstructive Bureaucrat: He spends his time denying Saavik and David a chance to check out the life on the Genesis Planet, and when he does he continues to harass them about it over the radio.
- Red Shirt: He and his ship, the Grissom, are destroyed for being in the wrong place at the wrong time.
The captain of the Excelsior prototype. Rather arrogant and in over his head.
- Character Tic: Carries a swagger stick (similar to George S. Patton) wherever he goes. Scotty finds it particularly annoying.
- Jerkass: Very smug and overly proud of the Excelsior's abilities. He boasts to Scotty that he hopes to beat some of the Enterprise's speed records.
- Named by the Adaptation: His first name comes from the novelizations.
- The Rival: To Kirk. There are shades of this in the film but the expanded universe, particularly the novel Prime Directive, really runs with it.
- Shadow Archetype: Styles is essentially what Kirk would have been like if he had focused more on Starfleet politics and career ambitions instead of passionate space exploration and cowboy diplomacy.
- What Happened to the Mouse?: Styles was intended to return for Star Trek IV: The Voyage Homenote , but actor James B. Sikking was unavailable to reprise the role, so the finished film only features exterior shots of the Excelsior. By the time of Star Trek VI: The Undiscovered Country, Sulu is Captain of the Excelsior with no indication of what happened to Styles. Expanded universe material suggests that Sulu was given command of the Excelsior after Styles was killed in action.
- Be Careful What You Wish For: He spends a full minute griping to Uhura about his boring assignment, saying that he needs "some challenge in [his] life, some adventure...maybe even just a surprise or two." Uhura gives him this warning shortly before pulling a phaser on him and making him sit in a closet.
- Kind Restraints: In the novelization, the main reason why Uhura locks him in the closet. It was meant for his own protection and not to implicate him in the plot to steal the Enterprise. In fact, he even gets an apology from Uhura in the novelization before she flees to the Vulcan embassy. Uhura knows that "Mr. Adventure" would be publicly humiliated, but it was better than being court-martialed.
- Authority Equals Asskicking: Comes across as noticeably stronger than Kirk when the two of them trade blows in the climax of the film, even No Selling multiple blows from a large tree branch.
- Bad Boss: With a side of Even Evil Has Standards, though. He executes his original gunner for "accidentally" destroying the Grissom, though seems rather disgusted that the gunner showed no remorse in blowing up a defenceless science vessel, and instead bragged that he got a lucky shot. Subverted later when he is visibly grieving for what he sees as the senseless and honorless death of his crew.
- Beard of Evil: Sports a Fu Manchu mustache and beard.
- Blood Knight: Kruge was basically the prototype for the TNG-era "WAAAGH!" style of Klingons.
- Disney Villain Death: A variation, as we do see his body explode into a fireball when he lands in a lava pit.
- Establishing Character Moment: He establishes his ruthlessness in his first scene by blowing up the smuggler ship for outliving their usefulness, along with his lover for knowing too much.
- Even Evil Has Standards: His immediate goal is similar to Khan's in the previous film, but where Khan was ruthless and willing to resort to senseless torture and murder to get his way, Kruge tries to keep enemy casualties to a minimum, initially because he needs prisoners who can explain Genesis to him, but he at least sounds willing to take Kirk's crew captive rather than destroy them outright. He's even willing to give Kirk two full minutes to announce his surrender to his gallant crew. On the other hand, and again unlike Khan, Kruge is very much a Bad Boss to his own crew.
- Leeroy Jenkins: He starts a firefight against a battle cruiser-level starship that outguns him 10-to-1 using his cloaking device and the element of surprise (while still expecting to lose the fight), then when instead the captain starts negotiating with him, he realizes there is something seriously wrong with the ship and sends over half his crew as a boarding party to take control.
- Noble Demon: Is outraged after his gunner disregards his order to cripple a presumably unarmed science vessel and opts to destroy it outright, showing no remorse in doing so: Kruge calls him an 'animal' after vaporizing him. Later, he's shown in a Villainous BSoD when he realized he sent his crew into a trap.
- Him executing the gunner is expanded on in the Novelization, wherein he attempts to give the gunner an honorable death by ordering him to commit suicide, but the guy refuses, leading to Kruge shooting him.
- Not Afraid to Die: Kruge finds the prospect of fighting Starfleet's greatest hero captain on an exploding planet to be exhilarating. He's not purposefully trying to die, but such a death would be considered the most glorious end a Klingon could wish for.
- Pragmatic Villainy: He's furious over the Grissom's destruction, but only because he wanted prisoners.
- Samurai Ponytail: He has one, reinforcing the samurai elements of Klingon culture.
- Taking You with Me: Tries to drag Kirk down into a fiery chasm, and before that he seemed quite happy with the possibility of dying with the Genesis Planet if Kirk wouldn't give him the info he wanted.
- Withholding Their Name: Commander Kruge's name is only spoken by Valkris two minutes before she's killed; his troops only address him as "My Lord" or "Sir", and he flat-out refuses to tell Kirk his name.
The First Officer of Kruge's Bird of Prey.
- Aliens Speaking English: Averted, which leads to the death of himself and his boarding party when none of them realize that the computer is counting down to self destruct. The novelization states that he assumed that the computer was chiming the time, and chocked it up as an annoying human affectation.
- Beleaguered Assistant: Nearly gets vaporized by Kruge in the aftermath of the Bird-of-Prey's first gunner getting blown to shreds, after Torg attempts to reveal the existence of David, Saavik and Spock on the Genesis Planet.
- The Dragon: Appears to be Kruge's second in command and the only officer that Kruge trusts with his plans to take Genesis.
- Fatal Flaw: If only he understood Arabic numbers, he might have been able to call for a beam-out in time. Unless he was just Too Dumb to Live.
The Second Officer and de factor Chief Engineer of Kruge's Bird of Prey.
- Death Seeker: The film leaves it ambiguous as to whether he actually wants to die after the rest of his crew is killed, or whether he's just annoyed that Kirk is screwing with him. The novelization of the film makes it more explicit, and he commits suicide before the captured ship reaches Vulcan.
- Real Life Writes the Plot: Maltz was going to return during the trial of Kirk and McCoy in Star Trek VI: The Undiscovered Country; he was going to testify about their actions in stealing the Klingon scout ship. Laroquette was unavailable at the time of filming so the scene wasn't done.
- Sole Survivor: The only surviving member of the Bird-of-Prey crew, most of whom get blown up with the Enterprise, and the remainder of whom are killed down on the Genesis Planet.
- Taking You with Me: Refuses to help the Enterprise crew fly the captured Bird-of-Prey to safety, likely happy in the knowledge that they'll all die when the Genesis Planet goes boom. Fortunately, Scotty and Sulu work out how to fly it anyway.
- What Happened to the Mouse?: He has never been seen again in the canon film/TV universe. His fate past this film depends on the writer in the Expanded Universe. The novelization of the next film says he did eventually commit suicide. But other EU books see him appear alive. And as noted above, he was originally going to appear in VI to testify against Kirk and Bones at their show trial.
A Klingon spy working for Kruge.
- Disposable Woman: Subverted, as it's Kruge himself who disposes of her, though their exact relationship is somewhat ambiguous.
- Face Death with Dignity: She reacts to the news of her impending demise with a relatively calm "Understood."
- She Knows Too Much: She, and the crew of the freighter she's on, get blown to shreds after she reveals that she looked at the Project Genesis briefing.
- It Has Been an Honor: "Success, my lord... and my love."
A Klingon warrior serving under Kruge.
- Dull Surprise: His reaction to almost everything, from Kruge killing the giant worm creature to the shocking sight of the teenage Spock rapidly aging into an adult.
- Mook Lieutenant: being a Klingon non-com and all.
- No Name Given: Not even in the novelization.
- Small Role, Big Impact: He is the one who murders David.
- Spell My Name with an S: Well, his rank, anyway; in the film credits he's "Klingon Sargeant," while in the novelization he's a "serjeant." Both are acceptable variations of "sergeant," though.
The (first) gunner aboard the Klingon Bird-of-Prey.
- Asshole Victim: None of his fellow Klingons feel sorry for him when Kruge shoots him as punishment for insubordination.
- Beleaguered Assistant: Even before Kruge kills him, he's the one with the unpleasant task of feeding his leader's ferocious pet dog monster.
- No Name Given: Like the sergeant, he isn't named in any media.
- Small Role, Big Impact: It is his destruction of the Grissom which forces the Klingons to search for hostages down on Genesis.
- You Have Failed Me: With a side of Even Evil Has Standards; when he "accidentally" blows up the Grissom after being told to simply cripple her, and then compounds his mistake by bragging it was a "lucky shot," Kruge shoots him.
The replacement for the Bird-of-Prey's original gunner.
- Karmic Death: After firing the shot which cripples the Enterprise beyond any immediate hope of repair, he ends up being among those killed when the ship self-destructs.
- Small Role, Big Impact: He only has a single line of dialogue and a very brief amount of screentime, but he fires the shot which completely fries the main systems of the Enterprise, forcing Kirk to destroy her.
- You Have Failed Me: Averted in his case as he's very careful to avoid the fate of his predecessor. When Kruge orders him to disable Enterprise (with a clear threat of what will happen if he also gets a "lucky shot" like the first guy) he understands his orders quite clearly and aims very carefully. It helps that unknown to him Enterprise is undermanned and running on a very precise automation system that fails at the slightest damage. He was actually about to keep firing until Kruge stops him.