For characters who debuted in Star Trek: The Original Series, see Characters.Star Trek The Original Series
A Vulcan cadet serving as Spock's second in command.
- The Apprentice: Spock's protege.
- Bothering by the Book: Has the audacity to cite Starfleet regulations at Admiral Kirk. After the Enterprise is nearly destroyed because Kirk ignored her advice, Kirk orders her to keep on citing regulations at him.
- Dark and Troubled Past: The novelisation explains that she was sired by a Romulan from a Vulcan prisoner, and grew up on the fringes of the colony as a starving child thief until Spock rescued her.
- Demoted to Extra:
- She is a major character in The Wrath of Khan and The Search for Spock, makes a brief appearance in only one scene in The Voyage Home, and then is never seen again.
- She was intended for a major role in The Undiscovered Country, but between casting difficulties and objections by Gene Roddenberry over an established character becoming a traitor, her name was simply used as a placeholder for Kim Catrall's character, Valeris.
- Green-Skinned Space Babe: Downplayed. Attractive, yes, but dressed rather conservatively for the trope. (A Starfleet uniform is hardly Victoria's Secret.)
- Naïve Newcomer
- Not So Stoic: She's young, so it comes as no surprise that she's often barely keeping a lid on her emotions. She's skittish and prickly during the Kobayashi Maru test, and she's clearly nervous later when talking to Kirk in the elevator. In a Deleted Scene, Spock tells Kirk she's half Romulan, but the canonicity of that has been debated ever since (the novelization confirmed this and expanded further on her background, but novelizations always come second to the movies themselves in terms of canon).
- The Stoic: She's a Vulcan, so it comes with the territory. The novelisations have her Not So Stoic due to her Romulan half-blood, but it's downplayed in the films.
Scotty's nephew and Starfleet cadet.
- Ensign Newbie: Just like the other cadets.
- Nerves of Steel: While Engineering was in chaos, he helped save at least one of the other engineers. As his uncle said:Scotty: He stayed at his post while the trainees ran.
- Sacrificial Lamb: His death hammers in how seriously Kirk screwed up in his first showdown against Khan.
Regula I Personnel
- Armies Are Evil: Very ambivalent about working with Starfleet due to concerns with how they would use his research.
- Cynicism Catalyst: Kirk was ambivalent about Klingons throughout TOS. After David's death in Star Trek III: The Search for Spock, Kirk would start harboring a deep hatred of Klingons, which almost lands him and the Federation in trouble in Star Trek VI: The Undiscovered Country.
- Heroic Sacrifice: He tries to stop Saavik from being executed by a Klingon.
- Luke, You Are My Father: The son Kirk had never met. He'd stayed away, respecting Carol's wishes.
- Properly Paranoid: Doesn't like working with Starfleet because of how the Genesis research could be abused as a weapon. Sure enough, the Genesis project staff are largely murdered and the device stolen to be used as a weapon by Khan, which wouldn't have happened if the USS Reliant didn't stumble across his Lost Colony while doing scout work for the Genesis Project.
- Sacrificial Lion: Somewhat erratically so. Sometimes Kirk agonizes over his death, yet at other times he seems to shrug it off, or even forget him entirely. For example, in Star Trek V: The Final Frontier, it's strongly implied that Kirk's secret pain is failing to save David, and yet, in Star Trek: Generations, Kirk expresses shock that Sulu has a grown daughter, wondering when he had time to do so what with his career. On the surface this overlooks the fact that Kirk also had a grown child; but on the same token he wasn't in David's life, so regret over not having a family of his own could still apply.
- Sour Supporter: Is eager to express his displeasure with the situation, both before and after Khan makes his appearance.
- Walking Spoiler: Mostly centering around the events of The Search for Spock.
- What the Hell, Hero?: Saavik verbally kicks his ass when she finds out that he cut corners to solve a few logistical problems with Genesis and pointedly blamed him for the deaths of the crew of the Grissom. Poor David spends the rest of his life in a Heroic BSoD.
- A God I Am Not: Fully realizes the Genesis Device's destructive potential. Insists that "There can't be so much as a microbe, or the show's off," since she rationalizes what would have happen humans if such a device had been used on Earth.
- Badass Bookworm: Obtained a doctorate in Molecular Biology which helped her and her (and Kirk's) son develop the Genesis device.
- New Old Flame: Mentioned as "that little blonde lab tech" that Gary Mitchell set up with Kirk, as a distraction for Kirk's class at Starfleet Academy.
One of the Augments serving under Khan.
- Battle Butler
- Expy: He's the Starbuck to Khan's Ahab.
- To David Marcus. Both are younger men subordinate to an older man who acts as a parental figure to them, but while David is brash and wants nothing to do with Kirk (at first), Joachim is reserved and has Undying Loyalty to Khan.
- While the film leaves it ambiguous whether Joachim is meant to be Khan's son or not, the Expanded Universe explains he's his adopted son, raised by Khan after his parents (his father being Joaquin from "Space Seed") were killed in battle.
- Also a foil to Saavik. A younger crewmember who tries to be the voice of reason to their overconfident leader, only to be ignored with disastrous results. The key difference is that Kirk first ignores and then listens to Saavik, while Khan first listens to and then later ignores Joachim.
- Mook Lieutenant: Not really physically intimidating to be The Dragon, as Khan does all his own interrogations. He just exists to allow Khan to awesomely monologue to someone.
- Morality Chain: Joachim tries to be this to Khan, but it doesn't really take.
- Only Sane Man: Granted, he's the only speaking member of Khan's crew so we never really find out what his other followers think, but he's certainly the only one who actually stands up to Khan.
- Punch-Clock Villain: Played with, he is a very willing accomplice to the theft of the Reliant, and does go with Khan's plans to attack the Enterprise, but it's pretty clear he would just as soon take the Reliant and Genesis and take that as a win without hurting anyone.
- Or just as validly, he could see where Khan's destructive obsession with Kirk would lead, and was trying desperately to steer his leader away from potential suicide. He was just too loyal to Khan to flat-out pull a Screw This, I'm Outta Here! on him.