"It's widely believed that a Contractor possesses a cool, analytical mind: at all times, in all situations, no matter how desperate, he's able to calculate the most logical course of action. Is it because he knows no fear? Hardly. A Contractor can get as scared as anyone. He simply doesn't let his feelings affect his reason."
Everyone has a tipping point, a Berserk Button, a threshold of shock and joy and weirdness that once crossed collapses all emotional reserve like a Fawlty Towers Plot. Some, however, have such an exceptionally high threshold that they'd probably greet the impending collapse of the universe with the same equanimity as cold tea.
Characters with Nerves of Steel are of steel in the same way a physical body can be Made of Iron — they are nigh-unshakable.
Someone who has Nerves of Steelthinks when times are tough. He makes decisions efficiently; he pushes his emotions aside, and so his decisions are not overly affected by them. He may be The Stoic, or he may be perfectly normal emotionally. Either way, his mind is never shoved aside when his emotion is. It is always thinking, a weapon as sharp as a sword. Characters with Nerves of Steel aren't intimidated by screams from those with a Hair-Trigger Temper, won't get upset if his Evil Plan is foiled (this is a morality neutral trait), he isn't likely to burst into tears when it turns out The Hero is Not Quite Dead and got better, and very probably won't even raise his voice to the man who murdered a Bus Full of Innocents unless the sound of his righteous ass kicking is loud enough to require it. Even happy news and emotions aren't likely to cause exaggerated reactions of joy (though he probably enjoys a nice hearty laugh every now and then). When captured, they are defiant and likely planning their escape.
Reasons for this demeanor vary. He's probably Seen It All, is naturally Spock-like, has an iron-clad Stepford Smiler facade (though on the inside they probably are banging his head against his cage) or emotionally can't be made to feel extreme emotion, such as the Tin Man. This doesn't count if the character is an Empty Shell, since there isn't anyone home to excite. The Extreme Doormat may count depending on the individual case (some are just too listless to care at all, not requiring any emotional control at all). Affably Evil villains and The Chessmaster are always composed as a result of everything going according to plan.
Even if this person doesn't have Psychic Powers; their control over their OWN brain often makes them resistant to those who do.
In short, someone with Nerves of Steel is immune to the Heroic BSOD, Villainous BSOD and Villainous Breakdown. God help us all if this proves untrue.
A good trait for a Badass Bookworm to have, at least if they want both halves at the same time. Note that nerves of steel may be hard to distinguish from Tranquil Fury at times. Showing a Stiff Upper Lip is a good way for a character to convince other people that they have Nerves of Steel. Compare Heroic Safe Mode, where the emotional/thinking part of the brain "shuts down" to allow for instinctual survival mechanisms to work unclouded by emotions. Post-Dramatic Stress Disorder is when a character fakes having Nerves of Steel, but breaks down as soon as the danger passes. Contrast Nervous Wreck.
Johan Liebert from Monster serves as a villainous example.
Nico Robin of One Piece should qualify. She's the one on the upper right of a previous page image not losing her cool.
Zoro and Sanji both probably count as well. Sanji's been shown to be very efficient at dealing with a rapidly crumbling situation and saving his fellow Straw Hats, Zoro never loses his cool (except at the other Straw Hats), but he's a little too happy to pick a fight with other swordsmen, and tends to consider options that are too extreme to be plausible, to qualify fully for this.
Mazinger Z: The Professor Gennosuke Yumi. Eighteen-meters-tall killer robots are advancing towards his Institute? Mount Fuji is about of erupting and burying them under burning lava? Squads of armed soldiers are besieging them under the threat of set off an earthquake under their feet if they do not surrender? A spy is aiming one gun towards him? He has been captured and is being used like hostage? It happens all the time! Basically Yumi is a scientist, hence he refuses panicking and instead of it he uses his analytical mind to study the trouble and find a solution quickly. He is so good keeping his cool he can come across like cold and aloof sometimes. Usually he only expresses emotion when one of the kids -Kouji, his daughter Sayaka or their friends- are in serious and immediate danger.
Usually you would not associate Kouji Kabuto with this trope since he is a Hot-Blooded character, but he is surprisingly good keeping his coolness when he needs thinking quick to save himself or someone else.
UFO Robo Grendizer: Prof. Umon also plays this trope. He can be incredibly calm in the worse situations (or his anime version is. One of his manga versions... not so much).
When Uryuu lost his powers, he learned that the only way to regain them was to have a giant flaming energy arrow fired into an exact location 19mm to the right of his heart. This could only occur while he was putting his life on the line so that both his body and spirit were stretched to the absolute limit. In other words, not only did he have to be shot in a location that would kill him if even a millimetre wrong, but he had to be a moving target for it to work. His father, Ryuuken, who had to perform the shot, made it look easy solely because he didn't turn a hair when doing it. Later on, when he leaves the room and lights up a cigarette to relax, the moment strongly indicates it wasn't easy for him at all, he was simply that good at disciplining himself when it mattered. Fridge Brilliance perhaps as Ryuuken is also an extremely talented surgeon, a job that requires nerves of steel every day.
To everyone's surprise, Mizuiro turns out to have these. When he wakes up in a town that's been thrust into the spirit world and is therefore practically a ghost town, he reacts by stocking up on essentials - rations food, tasers and other weapons. When attacked by a being that can literally vaporise things at the touch, he nonchalantly throws a bottle at him to test the enemy's capability. Upon realising that the rumour about this being vaporising things is true, he doesn't bat an eyelid and coolly throws a Molotov cocktail at him instead. He's only mildly surprised that it doesn't work and, for a moment, his companions are actually more nervous of him than they are of the Big Bad.
Naruto: Itachi Uchiha. Every move is carefully calculated, and he never loses his cool. That Sanity Slippage from a couple years ago? He totally faked it so Sasuke would kill him. And then after being freed from Kabuto's control when he's resurrected, he helps Killer Bee and Naruto fight the resurrected Nagato and calmly figures out how to beat Nagato's then-unbeaten gravity attack. He then, still calm, announces he's going to go defeat the resurrection technique itself.
Gendo Ikari from Neon Genesis Evangelion. He only expresses emotion when his surrogate daughter Rei is in mortal peril or about to abandon him. He calmly assesses and discusses options about the situation while his actual son might be being boiled alive, or trapped in a dimensional pit, or about to attempt to attack him with a giant robot because he's tired of his dickery. At one point he's half-coated in blood by an Angel duel happening right in front of him, and he doesn't even flinch. It's not that he doesn't care; he does, deeply. He's just... very inexpressive. There's a certain amount of self-loathing there as well.
Black Lagoon has a number of characters who are remarkably good at keeping their cool under pressure, with Chang as probably the main example. He remains perfectly calm and collected even while a psychopathic killer is trying to kill or keep him pinned down with a machine gun.
Mobile Suit Gundam SEED: Lacus Clyne. The girl is never visibly shaken by anything that happens in the series, always maintaining a calm and cheerful demeanor... even when informed that her father has been assassinated, she carries on and does what needs doing. The only time she shows any loss of control is in a private moment near the end with Kira, where she breaks down crying from everything that's happened and hugs him. One scene later and she's back to her usual unshakable demeanor.
Haman Karn from Mobile Suit Gundam ZZ is famous for her iron composure, not even blinking when facing meters-long blades punching right at her face (because she knows that Judau would never kill an unarmed opponent). She loses her cool precisely once, after she shoots Judau's sister, and Judau responds with a gigantic phantom of pure psychic rage, causing her to break and run away as fast as she can.
Akagi. His inability to become scared or upset about anything eventually drives the Big Bad (whose playing style is partially based on frightening his opponents to a point where they begin to play desperately) into a Villainous Breakdown.
Soldiers using the 3D Maneuver Gear properly in Attack on Titan need to be able to react and change directions in an instant to avoid disaster while maintaining perfect balance. Levi, who is the World's Strongest Man, is consistently stoic and calm that it's near impossible to break him from that state.
Erwin Smith. There is a reason that he is Commander of the Scout Corps. Threaten him with execution? He will stand there and relay his entire plan to you so you can complete it when he's dead. Titan limbs flying around sending others scrambling for cover? He will stand there and watch without batting a lash. A Titan bites into his arm and drags him off? He will continue to yell orders to his troops, then show up later missing an arm, to save the day himself. He doesn't have a single nerve not made of steel.
Despite not being as smart as others on this page, Goku from Dragon Ball rarely losing his cool and remains calm even when the situation appears completely hopeless. While even Piccolo can succumb to panic or despair, Goku is usually seen thinking of a plan or even humoring how things seem hopeless while smiling. Among his group of friends he is often seen as the person to look to when things go really bad even when he is not currently the strongest fighter.
Albert Cleary of Damage Control, who serves overdue bills to Dr. Doom without showing any outward signs of duress.
Post-Parallax members of the Green Lantern Corps tend toward this, since they are now selected not for their lack of fear, but their ability to overcome it.
In the My Little Pony: Friendship Is MagicShip FicTwilights List, Rainbow Dash thinks Twilight has these because she acts so cool and unperturbed in the face of Rainbow Dash's anxiety over the date. Unfortunately, this was because Twilight was actually asking Rainbow Dash out on a practice date, and as such, doesn't have any reason to be nervous. When Twilight realizes what has happened, she freaks out.
Charles Morse in The Edge shows impressive self-possession while stranded in the Alaskan wilderness.
Charles: You know, I once read an interesting book which said that, uh, most people lost in the wilds, they, they die of shame.
Charles: Yeah, see, they die of shame. "What did I do wrong? How could I have gotten myself into this?" And so they sit there and they... die. Because they didn't do the one thing that would save their lives.
Robert: And what is that, Charles?
X-Men: First Class: Sebastian Shaw knows how to keep his cool and respond logically to every new threat he faces.
This is most likely a requirement for Jaeger pilots in Pacific Rim, considering with what they fight against. One notable example is the Russian couple Aleksis and Sasha Kaidanovsky who calmly walk away when Gipsy Danger's plasma caster inadvertently activates. When the plasma caster is directly in front of them point blank.
This is described as the most important trait of a great gunfighter in Unforgiven.
Elysium: Carlyle is impressively composed when his Bugatti SSTO is shot down, and even sets an ambush, immediately after crash-landing, for Max and Julio by sending only one of his droids out to kill them, and waiting for them to leave cover before deploying the second. However, he (like Delacourt, and, it's somewhat implied, many Elysians), seems slightly robotic, which may be the source of his imperturbability. Mind you, he still had the occasional small spazz and yelp. It's still impressive that he wasn't screaming and flailing.
Ford Brody from Godzilla (2014). It takes brass balls to stay calm when the Mutos starts their rampage.
Horatio Hornblower : He displays these in war and in gambling. For example, at one point a lit explosive lands on the deck at his feet. He reaches down and calmly pulls out the fuse. He looks up and sees that everyone else had dived for cover, and they are now staring at him like he's the bravest man on the planet. He manages to be exasperated, because no other course of action had even occurred to him.
Scheherazade in the Arabian Nights. She spends nearly three years telling story after story after story, always ending on a cliffhanger, knowing that if it isn't a good enough cliffhanger, she will be executed in the morning.
Shows up, appropriately enough, in Nerves, where nobody really loses their cool despite a breeder reactor blowing up, producing an isotope that could destroy everything within thirty miles at any moment and the one guy who knows enough to stop it going missing. Interestingly, it slightly deconstructs this trope, showing just how hard it can be to keep calm and carry on.
In the often overlooked Frank Herbert novel, The White Plague, a character takes great pain and care to describe the titular illness in its every gory, incurable, detail, knowing that no one trying to cure the white plague can possibly do so. The reason this character has such intimate knowledge of the plagues effects is because she's dying of it.
The Dresden Files: Harry Dresden is normally exhausted, bleeding, in spiritual if not physical agony, angry, terrified and running out of magic with the fate of the world on his shoulders - none of which ever stops him from thinking and finding the answers he needs.
This trope is actually deconstructed in a side story from Murphy's perspective. The fact that he is completely unfazed by everything (among other reasons) is grounds for Murphy to be worried and/or scared shitless in itself.
Multiple characters in the 1632 series — notably among the uptimers Mike Stearns and Jeff Higgins. Taking examples from the first book alone:
When Mike Stearns realizes that there are soldiers coming to attack the Abrabanel's carriage, he intentionally stands out in the open with a semiautomatic pistol to draw their fire away from the carriage — and doesn't stop firing even when one bullet rips through his sleeve.
When Jeff Higgins is defending the students in the cafeteria from a charging band of (dismounted) Croat cavalrymen, he empties his shotgun, reloads, empties it again, and — not having time to reload a second time — butt-strokes another before finally being struck down by a saber-blow.
Susan Sto Helit of the Discworld thinks logically all the time (well, nearly all the time, as everyone has their blind spots) when others wouldn't — which means both in a dangerous situation and, let's face it, most of the rest of the time too.
In Unseen Academicals, Glenda develops these after she gets out of the crab bucket. Angry mobs? Furies? Vampires? The Patrician of Ankh-Morpork? She faced down all of them. Not to mention got into the palace using only pie.
In the X-Wing Series, Wedge Antilles is said to alternately have cold-space lubricants and ice water in his veins. He just about invariably keeps cool and adjusts to new situations. Certainly Wedge feels emotions, some strongly, but he's well able to analyze and understand them. He's only shown losing control once - when someone uses Fantastic Racism to diss one of his nonhuman pilots, who just died to save the man, he pulls a Neck Lift and never mind that the other man is taller.
Admiral Teren Rogriss, an Imperial fleet commander who ends up briefly working with the RepublicSolo Command, is noted to have these by his enemies. He amply demonstrates by playing chicken with kilometer-long capital ships. His Interdictor-class cruiser isn't much in a fight but can prevent a Hyperspeed Escape by Warlord Zsinj's flagship — as long as it remains in range. Zsinj sends several vessels against him but can't beat the Imperial-class Star Destroyers backing up Rogriss's ship, so he decides to set one of his cruisers on a collision course to force the (smaller and lighter) Interdictor to turn aside. Zsinj starts worrying the second he identifies the officer in charge, since he knows his own captain will flinch first. In the end, that captain is killed and the burning hulk of his ship is locked into its course. Rogriss stays past the last second, maneuvering out of the collision using a canny modification of his ship's systems, but also willing to take the risk that it wouldn't work to allow his allies time to keep fighting Zsinj.
P. G. Wodehouse's Jeeves; under the most strenuous conditions, he might be prompted to elevate an eyebrow an eighth of an inch or so.
Inspector Javert from Les Misérables is a really interesting take on this. No danger can shake his cool, calm reserve: he'll arrest an armed gang with a grin and a barrage of pithy one-liners, stare down the barrel of a gun and (accurately) predict it will misfire, duck hurled paving stones, and face his execution at the hands of angry revolutionaries with equanimity. Show him mercy when he's not expecting it, though, and it's a wholedifferentstory...
The prologue-only Ser Waymar Royce from A Song of Ice and Fire, book 1: A Game of Thrones, in spite of being something of an Upper-Class Twit, did not panic upon coming face to face with one of the Others. He calmly drew his sword and dueled the icy fiend, actually holding his own. He lost and wound up a wight, but still.
Stannis Baratheon is somewhat infamous for being dogmatically stubborn and cool under pressure. The fact that he doesn't seem to emote or react like most people do not help his already terrible PR.
Ender of Ender’s Game: despite the enormous pressure piled on him by the teachers and his almost complete isolation, he never loses his temper and keeps on studying and winning the games; even when he's confronted by an entire gang of bigger boys out for his blood, or when the teachers stack the games completely against him, he still doesn't panic and wins with brutal efficiency. In the final stages of his training he's so worn out he's one step away from going insane but he still keeps on winning every battle.
The Zombie Knight has Roman's secretary Gina. Without even being able to fight, she waltzed into a castle overrun with superpowered psychos from Abolish and riddled it with eavesdropping devices, then spent weeks holed up listening to the bug feeds (which often include the sounds of Abolishers gruesomely killing people) and feeding info to her allies. All while knowing that at any time a curious Abolish reaper might spot her soul and bring the supervillains down on her.
24: In spite of the worst that can be thrown at him, almost nothing phases Jack Bauer.
Babylon 5: Mr. Morden. Gotta hand it to him; not even being arrested, threatened by most of the cast or coming face-to-face with Ambassador Kosh seems to unnerve him. The fact that two equally advanced aliens constantly watch over him may have something to do with that — when Londo kills/chases them off, he finally cracks.
Simon is a classic Kuudere and is stoical a lot of the time. River had an even harder time in "Objects in Space". She had her amygdala torn out after all and thus is flooded with emotion
Wash is able to go from the funny sarcastic guy to completely calm and in control in mere moments as well, as best seen in the Pilot in where he shows us just WHY Malcolm and Zoe have such trust in him and provides us with one of the best Crowning Moments Of Awesome in the series by outmaneuvering the Reavers without losing that stoic calm.
Also in the Movie, outmaneuvering the Reavers while flying directly into the thick of an Alliance armada. When Mal panics and tries to direct him, "No, no, no, no!" Wash simply matches his tone, "Yes, yes, yes, yes!" and keeps his bearing.
Zoe walks into the room where her husband and her oldest friend and comrade are being tortured and cuts the villain off before he can even finish presenting his impossible dilemma, all without changing expression. When she gets given Wash and Mal's ear, she calmly accepts both, then returns to the ship and puts the ear on ice before heading back out for the rescue mission.
her response to Wash's death in Serenity is almost equally flat. She freaks out initially, but no more than a few seconds later, she is coolly walking off the ship, checking her weapons, and telling the others that "he's not coming."
Cristina: Derek's a mess, Meredith's a mess, you're a mess - that leaves me in charge! Now go. Scrub.In.
JAG: Clayton Webb has Nerves of Steel. While he can be annoying the only picture of him panicking was in a flashback in one episode. In other times he is never fazed.
Revolution: Julia Neville reveals herself to be in possession of these in "Nobody's Fault But Mine". She remains calm and states calmly that she's not the type to beg for her life...and this is while Miles Matheson is holding a sword to her throat.
John Watson. In the first episode, Sherlock mentions this trope by name while analyzing the man who shot a serial killer. At that exact moment, he catches sight of John and realizes who he's describing.
Sherlock has his moments, too. In the fourth episode, he's being threatened at gunpoint and is told that if he doesn't come up with a piece of information he doesn't have, John will be killed. Despite this clearly concerning him, he still remains relatively calm and thinks fast enough to deducethe information he needs.
It helps that Irene gives him a vital clue at that moment by looking down at herself.
And both of them handle the finale of the first season ender pretty well - particularly the last few moments.
In a Star Trek: TOS/Star Trek: The Next Generation/Deep Space Nine crossover novel, The Return, Dr. Bashir was doing some very delicate operation and the Red Alert klaxons went off. Data was sure that the patient was dead because the noise would have startled Bashir, but no, he kept his scalpel very still. Then he contacted the bridge. "Turn off the alarms in sick bay. I held myself still once but I don't think I could do it again."
And of course, Data does this. Though "Fiber optic nerves" would be more accurate in his case.
In Yu Gi Oh East Academy, every single one of the East Academy duellists shows an almost mind-boggling amount of courage, standing firm in the face of horrors that most war veterans would break down at. bear in mind that these kids are all underage schoolchildren who never asked for this.
In Blood Bowl, the "Nerves of Steel" trait means a player doesn't get any penalties from being surrounded by opposing players while handling the ball.
Deadlands has a character trait called nerves o' steel, but this Trope is more effectively represented by the level-headed advantage: the cool-headed hombre's lack of panic usually results in more flexibility with initiative in a combat round than others possess. Used well, a level-headed character can almost choose when to act in a round, representing a mind that is constantly looking for the perfect time to strike.
GURPS has the Unfazeable advantage, which means that the character in question never has to make Fright Checks.
The average Warhammer 40,000Space Marine has the rule "And They Shall Know No Fear", which lets them regroup automatically. (Provided, of course, they haven't run off the battlefield.)
The Fearless special rule takes this one step further; while And They Shall Know No Fear means the squad is always ready to come back for another go, Fearless characters and squads are never subject to Morale tests in the first place and cannot be broken, driven back, or suppressed. They can even be Tank Shocked (i.e. run at by an enemy vehicle) without ill effect, swiftly dodging out of the way and returning to their formation without losing cohesion.
Averted with Khornate berserkers (they of the "BLOOD FOR THE BLOOD GOD!!!" chant), who literally have no fear (thanks to crude lobotomies), but it manifests as frothing Ax Craziness. They also serve a god who doesn't particularly care who wins, as long as there's lots of bloodshed. So you end up with heavily armored madmen running directly into your guns and hacking away without a care in the world, and nothing you do will scare them off.
The Batter from Videogame/OFF definitely counts, apart from when he's purifying spectres.
JC Denton is Deus Ex, when playing stealthily. "You mechs may have copper wiring to reroute your fear of pain, but I've got nerves of steel."
The protagonist in Metro 2033 is resistant to psychic anomalies. At least a few times in the game, he and several others are attacked by something indescribable and unnatural and he's able to resist it. This is also why he's able to withstand the Dark Ones's psychic communication without going insane.
The Warrior of Light from Dissidia: Final Fantasy almost always keeps a cool head no matter the situation. He's only shown losing his calm demeanor once, when Cosmos sacrifices herself to shield him from a horde of Manikins near the end of 012.
Tales of the Abyss has Jade Curtiss as the Stepford Smiler version of this. His ability to be unfazed by any situation is occasionally lampshaded by the younger characters as something that freaks them out.
CommanderShepard, especially if the Sole Survivor background is chosen. Keeping his/her cool while the rest of his/her unit panicked under attack from nightmarish Thresher Maws was what got him/her noticed enough to be considered for the Spectres. Ditto his/her feat in the War Hero origin, where Shepard effectively stared down an entire invading army until reinforcements arrived.
Joker's performance in general, and at the end of the first game in particular; he isn't even nervous trying to land the Mako APC in a fifth of the normal minimum landing zone, just intent. It's a stark contrast to his attitude outside of the pilot's seat, though.
Dante from Devil May Cry. This guy's reaction to things like giant demon birds threatening him, a three headed ice dog trying to block his way, or a demon snake trying to eat him? Dodging or no selling whatever they try and taunting them.
Shu Shirakawa in any Super Robot Wars games where he's present is this. Doesn't matter even if he's already on the verge of being defeated, his expression will not budge one bit.
A questline in Grand Theft Auto V has Trevor helping a pair of lunatics threaten and arrest anyone they think is an illegal immigrant. The last mission starts with Trevor running into one of their previous victims on the street, and is informed that the man's family as been living in the US for two hundred years. Trevor tries to play it off, but the argument escalates until Trevor is pointing a gun at the man's head. He doesn't flinch, and tells Trevor that if he wants to make things right, he'll take care of the men he had been working with. He then tells him that he won't pay him a single penny for doing so. Trevor, easily the most psychotic and violent GTA protagonist, can do nothing more but honor his demands.
Phoenix Wright from the Ace Attorney franchise. He's generally easily spooked or disheartened, but characters note time and again that he's at his best when under pressure and true enough he is pretty much unflappable once he gets going.
The protagonist from Persona 4 has them, even more so should you pick the right dialogue choices. Not to say he doesn't show emotions like confusion or panic, it's just that he manages to stay calm and collected regardless. When emotions run high, he often gets the option to tell the others to calm down. In fact, late in the game, telling the others this is crucial should you want to avoid the first Bad Ending.
In Fate/stay night, Servant Archer is singled out as having these more than any other Servant due to cultivating battle experience as a way to make up for the fact that he had very few natural gifts.
Servant Assassin also has shades of this. Possibly it's due to his Extreme Doormat nature, but things like having his lungs detonated from the inside, being minutes away from death due to Mana deprivation, or being eaten alive don't seem to affect his mind much.
In the prequel, Emiya Kiritsugu is also an excellent example.
Johny, the super mellow teenager, from the Flash series Siblings.
Chaz the talking sword form Sluggy Freelance is always ready to neutrally analyse the current situation. He being just a sword, it's not so surprising he doesn't get upset about things, although he can certainly be sarcastic.
Even in a city full of superheroes and supervillains, Skitter is an exceptionally cool customer. It's particularly evident in her fight against Mannequin, one of The DreadedSlaughterhouse Nine — she comes up with her plan of attack literally while he is trying to slit her throat.
One of the reasons Tattletale is so ferociously effective is that she doesn't let pain, injury, or threat to life and limb stop her from using her smarts, her superpower, and her vulpine grin to break down any obstacle in front of her.
Jessica Yamada, introduced in Interlude 18 (Donation Bonus #3), is an unpowered therapist specializing in working with superpowered individuals, most of whom could kill her as easily as swatting a fly. Even in the face of intense fear, she maintains a calm demeanor for her patients' benefit.
The As Himself version of Doug Walker in "The Review Must Go On". His character has, to be blunt, come to life and is scaring the shit out of him by acting like some demonic abusive partner, but he only shows his terror when he's scarfing down tranquilizers alone in the car.
Rebecca from Demo Reel responds to creepers in masks telling her to be scared by reminding them that their car is being towed.
All of the main cast of Chrono Hustle fits this, but it's especially notable with Mary Bishop. Jack Masterson is a con artist, and thus is used to thinking his way out of tricky situations. Melinda Summers is a TRD agent, and is thus trained to deal with all sorts of strange things. Mary, meanwhile, is just a simple farm girl from the Old West, who manages to deal with a crew of pirates when she accidentally ends up in that era.
A villainous example is Lex Luthor in Young Justice, Lex never once loses his cool, and always stays calm even though he is targeted by the real Roy Harper who is out to get revenge on him.
In Gravity Falls, when a gang of 15-year-olds is held captive by a duo of vengeful Reality Warper ghosts, Wendy is the only one to get scared but not panicked. Even Dipper, who ultimately saves the day, has at least one freak-out.
Transformers Prime Soundwave. Nothing scares him. Whether it be an Autobot rampaging though the halls of the ship, one of the Wreckers charging him head on, or what was for all intents and purposes a Terrorcon apocalypse, he always handles the situation calmly and efficiently.
The former earned his nickname specifically from The First Battle of Bull Run (a.k.a. First Manassas), when his brigade was one of those that came up to hold the line after the initial attacks of the Union had driven other Confederate troops off in disorderly retreat. While the nickname was a compliment of his courage ("There is Jackson standing like a stone wall"), what makes particularly clear that the trope fits is the place where his brigade was standing like a stone wall: just over the crest of the hill, where the Union artillery fire could not ravage them. (What's more, his cannon were placed just on the crest, meaning the recoil sent them backwards out of the line of fire for safer reloading.)
This is practically required of all medical professionals across the board. Surgeons work incredibly long hours under high levels of stress where the slightest shake of a finger or hand could cost a patient their life. Virologists and bacteriologists handle some of the deadliest biological agents in the world, the steadiness of their hands and laboratory regulations an absolute must in guaranteeing their own safety. Nurses and orderlies have to care first-hand for unruly, terrified, or dying patients, often seeing them through the most painful (or last) moments of their lives. There's a good reason why the burnout rate is so high in many medical fields.
Rafael Nadal is an interesting example. On one hand he's fiery and celebrates when a match is going his way and thus he is not stoic like many other examples, on the other hand the man never seems to succumb to pressure, even if the match is not going in his favour. Indeed, in the world of tennis, he's often lauded for his mental strength and composure.
Pretty much any sub captain who is reasonably good. Submarine actions are very slow and unlike some types of warfare, a sub captain cannot keep himself going by mere "Fight or Flight" instinct.
Try playing professional golf without this...
Or indeed any professional sport with a large cerebral component - cricket, baseball, snooker, the aforementioned chess...
In the 23-F coup attempt in Spain, in which troops stormed the Congress of Deputies and ordered all politicians to the ground - weapons pointed at them - three of them disobeyed: Manuel Gutiérres Mellado, who stood up and ordered the leader to desist (to no avail, but took some balls), Adolfo Suarez, who remained sitting down (also took some balls), and Santiago Carrillo, who remained sitting and calmly lit up a cigarette showing Nerves of Steel and balls of the same material.
Stockbrockers are so good at this, that the US Navy considered them a background occupation of choice for Fighter Direction Officers during World War II. It was believed someone who could handle the stress of bargaining on Wall Street is likely to be good at directing air traffic in a carrier battle.
It was also about having experience in quickly allocating resources.
Michael Jordan was magic in the clutch because of these. It's really this attribute, more than his other-worldly skills and athleticism, that set him apart from all his peers. Even if he came up short, it wouldn't faze him at all next time.
An unwritten item on the essential qualifications list for commercial and military aviators, emergency responders and pretty much every other profession you can name where the smallest panic-induced mistake can cost lives.
Truth in Television: Scientists have identified a gene named COMT which has two variants, often called the "warrior" and "worrier" variants. People who have two copies of the "warrior" variant tend to exhibit this trope; their ability to concentrate, reason, solve problems, etc. actually increase when they're under stress. On the other hand, people who have two of the "worrier" variant tend to perform better than most people under normal conditions, but fold like a cheap lawn chair under pressure.
The more horror movies you watch the more likely you are to become used to jumpscares and the less likely they are to startle you.