Lone Wolf and Cub is practically constructed of these and Crowning Moments of Awesome for the main character, Ogami Itto. Oh Crap faces generally come up more or less every time someone either recognizes Itto or he reveals himself, generally by pulling out his sword, running at somebody, and shouting "Assassin, Lone Wolf and Cub! I come for your life!"
In the case of the latter, Oh Crap is an understatement.
It happens many, many times in Mazinger Z. A good example was when Baron Ashura was relaxing in his/her submarine fortress, feeling safe due to the knowledge of Mazinger Z could not reach him/her underwater because it had not been built to swim or dive... when one of his/her Mooks showed him through one screen Mazinger-Z was swimming towards them.
And in other episode, Ashura kidnapped Aphrodite A and examined it to learn how building a Photon engine. Later, when Mazinger Z broke into his/her base, a short-circuit burnt the computer they were using, destroying what information they had obtained. Ashura's expression was priceless (one of his/her Mooks got to drag him/her away because he kept staring at the ruined computer).
This is Dr. Hell's default expression in the final battle of Shin Mazinger, as every attempt to stop Kouji fails and more and more ridiculous rocket punches get thrown his way.
A more tragic example happens when Prof. Yumi and Prof. Gordon are talking about a Mechanical Beast that is sinking ships... and Gordon realizes his wife and their daughter are traveling by sea.
Used to great effect in Episode 9 of Steins;Gate when Okabe finds out just how much D-mail has changed the past.
In CLANNAD, where Okazaki Tomoya's face switches to this when he looked at Fuuko holding her starfish bread, (after everyone asked him to eat their bento, 3 full course meals each) telling him to pick the best choice (switching to Tomoya's face sweating). Cue Skip Scene to where Sunohara congratulates him and Okazaki suffering from a heartburn from eating meals from 5 people.
Of particular mention is when Light, after being revealed as Kira, pulls a piece of the Notebook from his watch. Near gets a look on his face that you can tell means he's realized Light will write down his name first. Matsuda fortunately shoots Light in the hand, saving his life.
And then there's the moment when Naomi Misora, having decided that Light isn't Kira, gives her real name in trusting confidence, and gets the full treatment when:
Naomi: "Light? Why do you keep checking your watch?" Light: "Because... I'm Kira."
Her expression immediately afterward says it all.
Also in the film when Ryuk shows his Death Note to Light, and it's his name that's written there.
And the manga, at the same moment, as Light realizes he's finally run out of options.
Mello makes a very satisfying Oh Crap face in the anime when Chief Yagami speaks his real name.
Smug SnakeQuattro, providing the image for this page up above, had this reaction twice in a row. First when she learns that Nanoha has found her location, then again a few seconds later when she realizes Nanoha plans to take the shortest route there. Video. Three if you count her reaction after she sees the actual beam speeding toward her.
Just to specify the 2nd reaction a smidge: Between them, Quattro calms herself by remembering that she's at the heart of the ship, filled with lots of hallways filled with drones, and that Nanoha can't possibly get to her in time. Then she notices Nanoha charging up a powerful magic attack, and wonders if she's planning on trying to blast through the ship, which is made to shunt magical energy. The second Oh Crap moment (complete with the above-mentioned face) hits upon remembering just who the hell she's dealing with, what the hell that person is capable of, and suddenly realizing the horrifying truth—Yes. Yes, she is.
Even before that, Vita had this reaction when Nanoha fires an attack that would make a Wave Motion Gun envious.
And even before that, Fate shows this reaction when, after barely surviving the aforementioned attack, she discovers that Nanoha has anotherWave Motion Gun. A bigger one.
Nanoha and Co. are on the receiving end in A's when they realize that the Book of Darkness, having absorbed Nanoha's magical abilities, is able to cast said bigger Wave Motion Gun at them.
Numbers cut loose. Fate appears. Fate stops the pursuit. Numbers wonder what's going on. And then it cuts to Hayate in the sky, casting a very ugly spell that we had all but forgotten she still had: Diabolic Emission. Oops.
A lighter version for Ginga in Episode 15, when Nanoha suggests a sparring battle of Ginga and the four Forwards (the new kids) vs. herself, Fate, Signum, and Vita. She seems to be just surprised at first, then it slowly dawns on her...
Ginga gets another one in Episode 26, just before Subaru Divine Busters the Numbers' brainwashing right out of her.
This AMV matches Nanoha's Oh Crap moments with Alucard's (mentioned below), to great effect.
Nearly as epic as Quattro's expression is the Oh Crap we get from Palus Abel in GaoGaiGar FINAL just before the unveiling of the Goldion Crusher. In the last stages of the final battle, the heroes have been put completely on the ropes and are now outnumbered hundreds to one thanks to Pisa Sol's regeneration abilities. Abel is as smug as she's ever been in the series... until she has this exchange with Soldato-J and Renais:
For those wanting to know: After getting beaten down by the heroes twice, Palus Abel orders Pisa Sol to put the Pas-Q Machine, their group's matter-regeneration device, into overdrive, reviving and cloning the Sol Masters en masse. This, however, drains the Pas-Q Machine, which their continued existence now depends on, of so much of its power that it is shut down for a period of time and left vulnerable to a strike from the Goldion Crusher. Just as the heroes had planned.
The Gunslinger Girl manga has a few of these, especially when mafia guy Cristiano sees that Rico has taken out his getaway driver and smashed his face into the window of the car.
In Zipang, a World War II American submarine commander has one of these looks when a modern-day Japanese destroyer that got sucked through time into the Battle of Midway manages to start its engines and move out of the path of two torpedoes from a dead stop, something ships back then couldn't achieve. He gets another one when he discovers that a fired ASROC (anti-submarine rocket), a modern-day anti-submarine weapon, has the ability to home in on his submarine.
Used for laughs when Keiichi and Rena catch Mion, Satoko and Rika trying to weasel their way out of a punishment game for losing a club activity. Extra points in the dub where Satoko actually says, "Aw crap!"
Higurashi no Naku Koro ni Kira: In Episode 2, Rika as she gets caught by the ropes of four of the villains that she was facing in her dream about becoming a Magical Girl, just before waking up from said dream.
Later, in the same episode, Takano gets this when Oyashiro Rika and Trap Satoko are about to destroy Nail Ripper with their 07th Explosion and send her flying into the wild blue yonder to become A Twinkle in the Sky.
"Not her! No!" Myotismon's reaction to Kari activating her crest, everyone. The original line was "Shimatta!" (Oh,no! /Damn!)
In Digimon Tamers the crew had been fighting "Devas", demi-gods based on the Chinese Zodiac. They'd defeated most of them, leaving a few left. What was it again? Oh, look, Henry's sister is talking to a very large rabbit Digimon, too far away from them to reach her. Oh right, one of the last Devas is a rabbit... OH SHI... Fortunately, Henry's sister manages to get past Antylamon's religious programming through sheer concentrated Moe.
Kurata from Digimon Savers gets a string of progressively larger ones when ShineGreymon reaches Burst Mode. The Oh Crap in response to ShineGreymon's Death Glare is the best one because it shows he realizes the tables have completely turned and now he's the one about to be repayed in full for all the death and destruction he'd caused. Arguably one of the most satisfying Oh Craps in history.
In Vision of Escaflowne, Dilandau has a particularly memorable one of these after Van goes berserk in the Escaflowne and destroys all of Dilandau's squad. It's easy to imagine that Dilandau may have wet himself during this, though we only see him from the shoulders up.
In Slayers Try, Xelloss actually utters this phrase when Amelia literally sings him into submission.
Basically every time some non-boss-level enemy realizes that the flat-chested girl he's been making fun of is actually Lina Inverse...
He screams in the French version too, but it's not THAT convincing.
In the fifth Slayers light novel, there's an excellent moment where Mazenda has Lina cornered outside of a burning inn. Mazenda is about to finish her off when Lina says that Xelloss is standing right behind Mazenda. Upon hearing Xelloss' cheerful "Behind you, Miss Mazenda!", she immediately flings herself into the burning building to get away. Lina narrates: "Now that, ladies and gentlemen, is fear".
In the first slayers series (episode 14), Amelia is used as a hostage. She tells Lina to forget about her and just defeat the bad guys. Lina says "Sure, sounds fine to me!"...cue the Oh Crap look from Amelia.
In Code Geass, one can argue Lelouch's worst enemy is Murphy's Law and not any of his actual enemies. When something goes wrong (usually when Suzaku decides to show up) he usually spends the rest of the episode Oh Crapping. Considering how often he makes the Oh Crap face, you can only imagine him making that face when he founds out the Cafeteria is out of Pork Buns.
Of course, Lelouch being Lelouch, the first five minutes of the next episode usually show him turning it back on his enemies. Only for something even worse to happen to him. Repeat cycle.
Sorry, but I feel the intense need to mention Suzaku's assault on the Knights of Rounds. Two of this trope within seconds of each other... And, I'm assuming, a couple dozen more when he laser spams an entire fleet out of existence between the aformentioned.
Suzaku himself has such moments whenever someone turns out to be equal in piloting skills to him. Pretty much any time he fights Kallen when she has a Knightmare on-par or better than his qualifies.
When Emperor Charles interrupts the ratification of UFN Resolution #1 (the liberation of Japan). He told them basically to BRING IT ON!
One good example of Lelouch having a moment like this is when The Emperor gets back up after being shot through the heart, and then Lelouch realizes that he is immortal and that neither bullets nor Geass work on him now.
Or when the Charles realize that he and Marianne are disappearing.
The most triumphant example was when Lelouch captured Damocles, effectively holding the whole world hostage to the fear of FLEIJA. That was a global "Oh crap!" moment right there.
Subverted at the end when Lelouch gives one on seeing Zero. Turns out it's all for show, and right before he's stabbed he gives a small, satisfied smile.
There's also the one in the first season finale. Nina suddenly appears in the Ganymede... which is packing an experimental sakuradite-loaded nuke. Lloyd instantly realizes what it is, freaks out like no tomorrow ("Ikenai!!") and yells at everyone to cease fire, followed by Rakshata realizing that if Lloyd Asplund is freaking, shit's about to hit the fan big time.
Guame gets an insanely epic one in Episode 11. He's effortlessly chomping on Gurren, when all of a sudden Lagann combines with it. Simon opens the top of Lagann and starts giving the most incredibly awesome Rousing Speech ever. Guame's expression is essentially frozen in an "OH SHI-" position for the entire scene.
Perhaps the best one in a recent chapter, when Ala Rubra (four of them, anyway) decide to crash Arika's execution.
Evil Chancellor: "Seize those rebels! Do not let those two in the valley escape!" Rakan: "Oh? You wanna get it on? You really think you've got the forces for that?" Evil Chancellor: "Do I have the necessary forces? You fool. The guards for this event are more numerous than those you see here. There are two entire fleets stationed over the surrounding area of tens of kilometers, not to mention elite troops numbering around three thousand. You may be powerful, but even you cannot..." Rakan: "Like I said. Are you seriously telling me... you think that's gonna be enough?"
In Chapter 292, Tsukuyomi's expression is most definitely this trope when Negi catches her trying to kill a member of the heroes. She can't actually say the trope, though, since Negi is holding her off the floor by a one-handed death grip on her neck.
Takamichi's expression in Chapter 99 when he realizes Negi is right behind him with a spell ready fits, although it is part pride in his friends son
Happens for the first time towards the end of the third chapter.
Envy: Lucky me! (knocks Ed out with a knee to the gut)
Played horrifyingly straight in Episode 41 of Brotherhood, in an expression most likely shared by the audience: After being blasted down a mine shaft by Kimblee, Ed awakens and painfully struggles to his hands and knees. The audience puts this down to him being Made of Iron, and of course he can handle one little mine shaft. Then blood starts pouring out of his stomach, and he looks back to see he's been impaled on a girder.
Mugear: "Ha ha ha ha ha! Didn't think I had the stones?" (transmutes bigass gun)
Ed: "Aw, crap!"
Hilariously used in the first anime during Ed and Roy's battle assement. After diving into the crowd for cover, Mustang smokes him out by calling Ed short, his well known berserk button , and the entire section of the crowd gives a collective oh crap face right before Mustang blasts them all.
Naruto, being a Shōnen series about ninja with magic powers, LOVES this trope.
Zabuza does this twice during Naruto's plan to free Kakashi from his water prison. Once when he realized Sasuke used the Shadow Shuriken Jutsu (though this was somewhat faked), and once more when the second shuriken transforms into Naruto and throws a kunai at him.
Inverted a few seconds later, where after usng his signature move Lee looks on in horror as Gaara's face starts falling apart, revealing that Gaara replaced himself with a sand clone. Gaara then shows up behind him, smiling and bloodlusted, which freaks out his siblings who know what he is like. The fight concludes with Lee's teacher and two other Jonin forced to step-in and prevent Gaara from killing Lee.
Sasuke realizing that trying to attack Danzo at the Hokage summit (with the other Kages and their bodyguards also present) probably wasn't one of his better ideas.
Kisame gets a hilarious Oh Crap moment when Killer Bee and the Raikage both go straight for his neck the second they meet up and cut his head off right as he's about to use a new technique.
Subverted when Kisame told them that they just beheaded a clone.
In a heroic example, "Oh Crap" seems to be Kenshin's default expression for a large part of his fight against Soujirou, with a particularly expressive one right after Soujirou dodges his "undodgeable" attack.
Kenshin himself also hands out "Oh Crap" reactions like candy, especially when people find out the tiny little redhead who's the sweetest, most polite person you'll ever meet was once the legendary Hitokiri Battousai.
An "Oh Crap" moment amplified by HSQ on the reader's side: Shishio takes everything that Kenshin, Aoshi, Sano, and Saitou can throw at him but refuses to go down.
Possibly the greatest example was when Shishio tauntingly points out that he thinks like Kenshin and was aware he was using himself as a distraction so "the insect" could assault the ship. Then he orders his men to open fire with a gatling gun on Sanosuke, who has nowhere to maneuver (for reference, it's been shown previously that a gatling gun works about as well on people in the anime as it does in real life). The look on Shishio's face when Sanosuke punches the water hard enough to create a burst that stops bullets?Priceless.
Shortly followed by another great example of Oh Crap in the series: After dodging the machine gun bullets, Sanosuke threw some explosives at their ship. The bad guys had just about enough time to reassure themselves such little things could not harm what is at that era the best technology could buy (for reference, the "ship" is a privately-owned Dreadnought)... Suffice to say, those are some high-grade explosives.
Shishio: "He's no insect!"
Nagi, at the very end of Mai-Otome, when everything finally comes crashing down on him and the Otomes come to capture him (even saying "Oh, crap!").
Though somewhat subverted in that he goes back to his passive "oh well" attitude anyway.
Which for all its beauty does not begin to compare to the manga scene in Part 2 where Joseph, taking part in a chariot death race against Wham, having all but miraculously beaten Wham to the epic warhammer waiting for them both on the stone pillar, cheerfully swings it round only to discover that Wham has upended the pillar off the ground and is swinging it at him.
In Part 5, Diavolo gets this one in spades when he figures out he is useless in the face of Giorno's new stand, Gold Experience Requiem.
In Part 2, Cars has a truly satisifying expression of panic on his face after he is launched into space and realizes that he can't return to Earth.
Expression of frothing rage on RobLucci's face, after hitting Luffy with his strongest attack, starting to walk away, being sure that his opponent is dead, and then suddenly realizing that Luffy is still standing, is frightening, rather than comical but contrasts with his previous calm and confident demeanor no less.
Regarding the war between the Marines and Whitebeard, we got firsthand evidence that Whitebeard wasn't someone to mess around with: one of his commanders was capable of effortlessly decimating a small fleet with a single attack, a pirate with a bounty of nearly 100,000,000 beri was downright inconsequential to him, and a minor clash between Whitebeard and Shanks was enough to split the sky. Then the war starts. Whitebeard has forty-two ships full of allied New World-based pirates, his fourteen remaining commanders have shown themselves on par with the likes of the Marine Admirals and Hawk-Eye (officially the world's strongest swordsman), and, oh yes, Whitebeard himself has a Devil Fruit power capable of leveling entire islands at a time, at the very least.
Expanding on the war, this expression runs through the whole thing, on both sides, as chapter after chapter there are indeed a lot of things to scare the crap out of people. Examples includes Whitebeard popping up right in the middle of the marine ships, along with his allies; Oz freaking junior showing up to kick ass; any and everything the Seven Warlords of the Sea do; and...an army of Kumas. Oh shi-
And rather notably, Sengoku, the master strategist who's basically planned out everything that's happened so far in the war, completely loses his composure when he finally sees Luffy using haki.
Whitebeard's pirates get this when Ace is killed by Akainu and Whitebeardis ticked off. Akainu himself gets this in the anime when he sees Whitebeard coming after him.
Buggy goes through several levels of this when it's revealed he was on Gold Roger's ship. Hilarity Ensues.
Fed up with Dracule Mihawk continuously chopping him into pieces during Chapter 561, Buggy shoots one of his Special Muggy Balls at him. Mihawk deflects the ball back at Buggy, giving us this priceless expression◊ just before it explodes in his face. It should be noted that it's one of the few moments where Buggy ever closes his mouth.
Miss All Sunday's words in Alabasta to Koza "You seem troubled but it's quite simple. Just think of the worst possible situation and you'll understand."
Played with when Nami tries to activate Tornado Tempo: first Nami herself gets one when her supposed ace-in-the-hole turns out to be what looks like another one of the Clima Tact's gag functions, then Miss Doublefinger gets one when said gag segues into the attack proper.
Hody's expression upon seeing Luffy knock out half of his army just using Haki.
In Bleach, this really is Tite Kubo's favorite artistic technique. Most battles alternate this moment. Fighter 1 will use an incredible technique, his opponent goes "oh crap", and/or reversed when the Fighter 2 was entirely unaffected the whole time and has his own awesome technique. Occasionally, whole crowds will do this, but usually only in Aizen's presence.
And when the situation was reversed in their last fight, at the end of the Fake Karakura Town arc. Right down to Ichigo cutting off Aizen's theme music. And Aizen realizing that he can't sense Ichigo's reiatsu because it's so absurdly powerful. Waaaay the hell more powerful than his. Or possibly even all of Soul Society put together.
In the anime version, the Septimo Espada Zomari LeRoux has a pretty good one right before he gets thoroughly thrashed by Byakuya Kuchiki. Heightened because Zomari's power is related to his eyes (all fifty of them), and his pupils dilate as he uses that power. So in the scene when he gets thrashed, there are actually a total of fifty eyes screaming "Oh crap!" The extra eyes are very apt, because it allows the viewer to see Zomari realize exactly how screwed he is.
Hitsugaya and Harribel go through several of these as they fight each other.
Also in the fight between Ichigo and Byakuya, just as Ichigo is about to die since he has reached his limit and cannot move, his Inner Hollow comes to the rescue, catching Byakuya's blade out of the blue, Byakuya face's at the time is the anime incarnation of this trope.
Despite being the epitome of The Stoic, Byakuya also does this when he realizes that Vandenreich have just utilized their ability to steal his bankai
One of the only times Ulquiorra's expression is anything but Dull Surprise or no expression at all comes when Ichigo rips his arm off, and this is pretty much the look he gives.
Even before then, this is clearly the look on his face when Ichigo bursts into the fifth tower at the start of their last fight.
In Chapter 354. Throughout the entire series, the Espada have been numbered 1 to 10. Yammy has been number 10. Then, he releases his Zanpaktou, and the number changes. It seems the Espada are actually numbered from 0 to 9. Guess which one is 0. The heroes' reactions fit this trope PERFECTLY.
Kyoraku's reaction to Wonderweiss hitting Ukitake deserves mention, his look of shock/rage being the only moment in the Starrk fight when he's not playing the flippant and underhanded fool.
Aizen, of all people, gets one when Shinji actually manages to hurt him. Somewhat subverted since, being Aizen, he almost immediatly regains his composure.
A huge Oh Crap moment for everyone occurs when they think they've defeated Aizen... and then they find out who they've really struck.
Aizen, once again in 414, after Gin impales him with Kamishini, leaving a fragment of it inside him. Gin then reveals the true abilities of his sword. The tables then turn when Aizen Came Back Strong and struck down Gin for his efforts.
Aizen in 417, most of all as he's telling Ichigo how there's no point in moving, and Ichigo is inferior. Aizen is interrupted mid-sentence and launched out of the city. His eyes say it all, and it gets even better in the next chapter when Ichigo blocks his attack one-handed without any effort at all, then breaks out of a fully-chanted level 90 kidou spell with even less difficulty. Aizen's expression before Ichi walks over and bitch-slaps him is... special. Aizen another one a few pages later when he realizes that he's not the one who's destroying the landscape with his own power leakage...Ichigo is. Before long, this degenerates into a full-on Villainous Breakdown.
Nnoitra managed to get one of these from Kenpachi of all people when Kenpachi seemingly impales him through the eye and out the back of his head...only for Nnoitra to continue talking, slide along the sword, and stab Kenpachi with his hand. Nnoitra then explains that Kenpachi never really stabbed him, his Hollow Hole is where his eye is supposed to be.
During the Soul Society arc, Renji has just achieved bankai and takes on his Captain Byakuya. With his bankai, he fights on par with Byakuya for quite some time. Byakuya then binds him with kido and reminds him that he too has a bankai. The Oh Crap expression on Renji's face is priceless.
Chapter 480 was an Oh Crap moment for all of us when we saw Shino about to be devoured by several gigantic and grotesque-looking Hollows. Poor Ryūnosuke...
Despite being a skeleton in his released form, Espada No. 2 Barragan Luisenbarn still gets this expression when he realizes that Soifon is about to fire her bankai, (Which, by the way, is a nuke-firing bazooka), into his face at point blank range, and he can't do anything to avoid it. He gets another one minutes later when his own aging power is uncontrollably turned against him
Tsukishima gets this immediately after Byakuya figures out away around his powers, and effectively blows a hole clean through his chest
No matter how strong the new Big Bad is, even he must feel a little bit of this when he sees Yama-jii's Bankai
Dragon Ball has many, many examples, but one of the most memetic is Cell in Dragon Ball Z. He's so ridiculously overconfident in the power of his "perfect form" that he's perfectly willing to sit still for four minutes while Vegeta powers up his ultimate attack. He doesn't realize his mistake until a half-second before the attack hits, where he actually exclaims "Oh shit!" (in English!) in the German dub. A nicely spliced version of the whole scene can be seen here. Unfortunately, he gets better, but had Vegeta's attack been a direct hit, he wouldn't have.
Heck, he was prone to this from the time of his first appearance. He gets the jump on Piccolo enough to disable one of his arms, and Piccolo "surrenders", but asks Cell to grant his final request and reveal who he is. Once he has complied with stating everything Piccolo needs to know, the latter tears off his useless arm and regenerates it at full health. And remember that at this point, Piccolo is much stronger than Cell; his only advantage was the element of surprise, which was now gone.
While he gets in his share of these situations himself (see above), Cell also loves to inspire Oh Crap reactions in others. For example, after he explains his plans for the "Cell Game" to Trunks:
Cell: I just can't wait to see that look of panic and fear. Trunks:(reacts in shock) Cell: That's it! That's the look!
There's also a less-popular, but equally awesome one with Cell. In his fight with Goku, seemingly against everything the main character stands for, Goku floats above Cell charging his trademark attack (mirroring the then-villainous Vegeta's actions earlier in the series by challenging Cell to either take the attack head-on or dodge it and allow Earth to be destroyed). At first, Cell thinks it to be a trap, but he keeps going. With every syllable, both Cell and all the outlookers look more and more dumbfounded at this desperate move, with Cell thinking it must be a bluff, especially since Cell doesn't actually need to breathe and thus would survive if he dodges. But then, just before release, Goku uses Instant Transmission (sorry, "Instantaneous Movement") to teleport away...right in front of Cell's face. Which contorts into an Oh Crap expression right before it gets blown off, along with most of his upper body. Refer to above spoiler.
Another good one is near the beginning, where Vegeta manages to cut off Oozaru Gohan's tail. His look of relief that he's finally stopped a major threat to him (the only one remaining, as he'd already incapacitated Goku) is very quickly replaced with an Oh Crap look as he realizes that a giant ape is now about to fall on him. And unfortunately for him, Gohan is still a full-size (although hairless) Oozaru when he hits. This leaves Vegeta vulnerable to Krillin, who normally would be a minimal threat to Vegeta even with Yajirobe's Absurdly Sharp Blade.
Dr. Gero's face just before Piccolo instantly knees him in the jaw.
Kid Majin Buu gets this look on his face when he realizes he's about to get hit by Goku's giant Spirit Bomb.
And then he gets an even bigger one when he realizes that he doesn't have the strength to throw it back again.
There are a number of these during the final Frieza fight on Planet Namek. Frieza trying to stop the Spirit Bomb that eventually blows him up (but fails to kill him), Vegeta suddenly realising how screwed they are moments before Frieza kills him in a suitably over-the-top fashion, Goku's reaction when realizing, after Frieza cut a huge fissure on the planet that Goku barely avoided, that Frieza's 50% of his power overpowering Goku was no bluff, and last but not least, Frieza's reaction to Goku going Super Saiyan for the first time.
Don't forget that time when Frieza just realized Goku had a reason for holding his arms in the air for so long while taking a beating...
And the best of them all: Frieza realizing truly how royally screwed he is against Super Saiyan Goku as his energy begins rapidly depleting in his 100% form. Also, the moment when Trunks reveals that he is a Super Saiyan as well — and then proceeds to shut down Frieza's best attacks (even his planet-killing Death Ball) without even breaking stride. And the look on his face before Trunks cuts him in half is truly satisfying.
And let's not forget the look on the face of Frieza's father, King Cold, later after his son's death, as he realizes that his begs to Trunks for mercy have fallen on deaf ears and that he's about to be blasted to pieces by his second God Breaker.
During the Buu Saga, Gohan and Goten are training, with Goten throwing rocks at Gohan. Gohan barely dodges one and has Oh Crap face #1. After a while, Goten asks if he could change into a Super Sayian like Gohan. Gohan brags about all the work it took for him and Goku to become a Super Sayian, only to have Goten go Super Saiyan like he was turning on a light. Cue Oh Crap face #2
The Supreme Kai reacts with horror when he sees that Buu is back in his originalform.
Piccolo: Makansap... Makakasapapa... Mekasapo... Oh, to hell with it. Special Beam Cannon! Goku: Is that what you're going to yell out when you OH GOD!!!
Vegeta actually gets three in episode 10, one in each part. First when evenly matched in a Beam-O-War with Goku only for him to pull a Kaio-ken times four, then when the Spirit Bomb misses but is deflected back towards him by Gohan, and finally when he cuts off Oozaru Gohan's tail only to realize he just knocked a giant monkey out of the air when it was right above him and he was too tired to get away.
Vegeta: I'm the best around! No one's ever gonna keep me down... oh NOOOOOO!!!
And in Episode 28 when Frieza No Sells Goku's Kaioken empowered Kamehameha.
Frieza: No seriously, kaio-what? Goku: Kai-Oh-Crap. Frieza: I thought so. [blasts Goku]
In Hellsing you could pretty much put everyone who fights Alucard, due to his fondness of letting his enemies blow him to bits and reforming. A particularly notable case would be Luke's, who spends the entire time between Alucard releasing his actual powers and being eaten wearing such an expression and sobbing in terror.
A slightly less horrific yet so very hilarious example comes from the 2nd OVA. Jan Valentine has butchered the entirety of the Hellsing organization, made it past Seras and Walter, and breaks into the conference room... only to find every member of the conference pointing a gun at him:
Hellsing book 7 has Seras Victoria going into Unstoppable Rage, and upon seeing that nothing can stop her now, vilainess Zorin Blitz has a big Oh Crap moment, just before suffering one of the most horrifying deaths ever seen.
Alucard himself gets one when, during his first fight against Father Anderson, he seemingly blasts him into submission then turns to check on Seras, only for Anderson to get right back up behind him, before running Alucard through with a blessed bayonet.
Don't forget Rip van Winkle when she senses the presence of Alucard heading for the ship.
A common malady among the more serious Ranma ½ foes is that, after delivering a deadly, massively destructive ultimate technique, Ranma somehow penetrates it and delivers his own counterattack to match, leaving the enemy staring in dumb shock and with their jaw hanging open. They don't even try to defend themselves or run away — they know they're screwed.
Unrelated example from the same series, as well as an inversion of a more common incident: Ranma jumps out of a third floor window, and finds out to his horror that there is a pool underneath.
Ranma: "Why'd it have to be water?!"
Pretty much everyone who isn't one of the three Noir maidens (or Altena) dies with an Oh Crap look on his/her face. So does Chloe, when she unleashes her inner Psycho Lesbian on Mireille and gets Kirika's dessert fork through the chest for her trouble.
If you ever hear Hallelujah Haptism laughing hysterically or telling you why you suck get your Oh Crap face ready. You're doubly screwed if he starts doing both at the same time, Unless you are Ribbons Almark or Soma Peries/Marie Parfacy.
The infamous cry above? Setsuna does it in the finale when Ribbons reveals the Reborns Cannon is actually a transforming Gundam.
The Movie has Setsuna having this reaction at what is apparently the now-dead Ribbons Almark walking straight towards him. It's an ELS that mimicked the body of a Ribbons-type Innovade and provokes this reaction once more when Setsuna blows away its upper torso with plastic explosives... and the lower body keeps walking.
He has a smaller one when he blows away an ELS ship with the 00 Quanta's Raiser Sword and proceeds to cut open the ELS planetoid... only for the planetoid to deflect the gigantic particle beam away from itself with no damage whatsoever. Good thing Graham happened to be nearby...
This page from Shigurui, when Seigen realizes that the guy is actually trying to hurt him; he's then blinded, in slow motion, bringing this into definite Eye Scream territory.
Then Shinji gets one in Episode 18, when the Dummy System is activated.
And again in Episode 19, when 01 runs out of power and stops working during a crucial point of the battle with the most powerful Angel yet, Zeruel. And he gets one when 01 starts moving again... as does everyone else!
Also in End, Asuka's expression becomes pure Oh Crap right before a (fake?) Lance of Longinus breaks through her Eva's AT Field to stab it (and her) in the eye.
Rebuild 2.0: Zeruel vs NERV, round 1.
Hyuga: "It broke through all 24 layers of special armor in one hit..."
In the manga, the JSSDF soldiers get a nasty surprise when they arrive to find Misato, slumped, fatally-wounded... and with a grenade pin hanging out of the corner of her mouth.
There's at least one in every episode of Evangelion, really. One of the rare funny ones is in the manga, when Shinji finds out that the girl who caused chaos at the arcade is his new coworker.
Although these reactions are prominent in Yu-Gi-Oh! 5Ds, notable ones occur when a Dark Signer brings out their Earthbound God, for two main reasons:
2.) They are huge, and hence their attacks are fatal if they connect.
Jack Atlus:(about to lose from direct attack by Imposter Jack Atlus) "Impossible!!!"
Imposter Jack Atlus:(after the real Jack brings out Savior Demon Dragon) "7000 ATK Points!?"
Jack has one when Yusei gets Stardust's attack to 5000 during their second duel in Season 1.
Yuusei's Riding Duel with Placido, after he finally Accel Synchros Shooting Star Dragon. He activates its effect, allowing it to attack a number of times equal to the number of Tuners among the top 5 cards of his deck. Placido's face becomes the epitome of this trope◊ when it's revealed that ALL FIVE OF THEM ARE.
When Team 5Ds finally figures out Breo's mysterious strategy: Deck Destruction.
Also occurs when they realise that Team Taiyo is about to bring out Sleeping Giant Zushin, a card with power akin to a God Card.
Yu-Gi-Oh! as a whole is quite fond of this trope. Usually it coincides with that particular season's Ear Worm playing in the background and the good guy's gambit (occasionally the bad guy's, but not often) paying off.
Kaiba has a funny Oh Crap moment when he nearly gets his head taken off by a possessed duel monster.
Evil Marik, when Jounouchi is STILL STANDING after taking Ra's attack head on. Kaiba too has one, but it's more of a "Holy Crap" than an "Oh Crap".
Marik again, in the Final Battle, when the Pharaoh declares a direct attack with Obelisk the Tormentor. (In the dub, Jonouchi makes a rather memorable joke: "Look, Marik is so scared his hair is standing on end! Oh wait, it's always like that.")
Haga during the Doma arc during the train top battle with Yami. After he reveals his cruel ruse concerning the shredding of a card supposedly containing Yugi's soul, Yami tells him to "wash his neck and wait". This is what they told prisoners who were about to be executed in Feudal Japan, so it's far beyond the "I'm going to kick your ass" point. Naturally after such a threat, Haga makes a face that pretty much says, "Crap, I'm totally fucked!"
That wouldn't be so bad if it weren't for the fact that, due to the Seal of Orichalcos, Haga actually physically felt the pain the monsters were dealing him, turning a children's card game into a No-Holds-Barred Beatdown.
Hell, the only reason Haga's torture ended was because Anzu (Tea to the English viewers) physically restrained Yami, begging him to stop. One imagines she was having a bit of an Oh Crap moment herself watching the man she had such a crush on turn into a homicidal maniac... as were, undoubtedly, more than a few viewers.
Yami Bakura in season zero has a great expression during the Monster World game when his dice cracks and breaks, letting Yugi and co. attack first and win.
Pegasus' face when Yugi summons Magician of Black Chaos. "Not him. Not now!"
Saiou's face in Yu-Gi-Oh! GX right before being attacked directly by Glow Neos qualifies as this.
As does Mask of Laughter's during his duel with O'Brien. He makes a mental boast about how he's going to win even with only 1000 Life Points left, draws for his turn...and sees O'Brien walking away with an activated trap, which he is forced to read to himself, leading right into a Crowning Moment of Funny.
Mask of Laughter: "Draw Bomb" ...when your opponent draws a card, this card...DEALS ONE THOUSAND DAMAGE TO THEM!?!THAT'S NOT FUNNY!! *explodes, LP meter rolls to 0 and razzes*
What makes it even funnier, is that the Masked Knight—and for a minute, the viewers—thought that O'Brien had given up an easy chance to win, and fallen for one of The Oldest Tricks In The Book, making the Masked Knight think he was going to make a fool out of him. In reality, O'Brien had done it simply to get the last laugh on him using Draw Bomb.
In Yu-Gi-Oh! ZEXAL, the look on Vector's face when Yuma summons C39 Hope Ray Victory is priceless. (Keep in mind, this came after one of the biggest cases of a Near Villain Victory on the current series.)
After the Major killed an entire squad of an elite police assault team within seconds and not only survived but eventually won a fight against a walking tank in Ghost in the Shell:Stand Alone Complex, the conspirators decide to have her permanently removed in the next episode. Not willing to lose more men in a futile attack against her, they send a single woman to kill her while her brain is transfered into a new cybernetic body. But instead of killing her immediately, she has to tell the Major what she's doing once the connections to her body control have been cut. But then someone reconnects the controls causing one of the two inactive bodies to rise. And she knows she doesn't stand even the slightest chance.
The big WHAM Episode when the terrorists stage their final action on the roof of a TV station skyscraper, with a news chopper circling them:
Reporter:"Swords! They are swinging swords and... AAAAHHH!!! Their heads!!! They just chopped off each others heads!!! Each of them! They killed each other! These men on the roof have murdered one another with swords!"
Smug Snake Isshiki gets one in RahXephon after he brings down the Tokyo Jupiter barrier... only to find millions of the Mu's super weapons and giant floating cities suddenly appearing world-wide. This leads almost directly to his Villainous Breakdown.
Kuki gets another one when Kunugi is about to trigger the second Tokyo Jupiter.
Kuki: "This cannot be... YOU WOULDN'T DARE! THEY HAVEN'T TOLD ME ABOUT THIS!!!"
The look on Conan's face when he realizes that the murderer he was confronting alone in the forest at night brought fifty armed men along with him to help dispose of the evidence. Cue Big Damn Heroes moment when Ran and then Makoto shows up and beats the crap out of all of them.
Hell, Detective Conan basically has the Oh Crap face as one of the show's stock facial expressions. To elaborate... someone having a scared facial expression without any reflection in their eyes? It happens Once an Episode.
Dallas's immortal expression at the end of Baccano!! when he realizes that the Gandor brothers decided to do what The Mafia does best and give him Cement Shoes. Gee, Dallas, looks like that Healing Factor won't be doing you much good now, will it?
Virtually every conversation Czeslaw has with Vino.
Pretty much everyone who confronts Kenshiro in Fist of the North Star will die with this expression on their faces, as Kenshiro explains to them how You Are Already Dead. Perhaps the most entertaining, however, was a Mook who decided he could use Hokuto Shinken. He didn't realize, however, that Kenshiro had already hit one of his pressure points. So he counts down...
It looked to me more like an incredible backfire, because it was the Mook's own attack and countdown. Basically, the guy who taught him was doing it wrong.
One of my favorites was when Toki paralyzed Kenshiro with his Hokuto Shinken and was giving his "The Reason You Suck" Speech. Then after Rei reveals he isn't the real Toki at all, and then...
Rei: "You may not know it, but in Hokuto Shinken, there are counters against attacks to pressure points."
Toki: "Wh-What... (Kenshiro begins to stand up again) Uukk......"
Pulled more than a few times in Zatch Bell!, but done best in Tio's battle against the extremely perverted Momon, who spends the ENTIRE battle pulling stunts like flipping up her skirt and stealing her panties from Megumi's bag. Then Tio learns a new spell that's fueled by Unstoppable Rage.
Because Youkai cling to life so tenaciously, and view hanyo with contempt, many of InuYasha's enemies get this reaction during or just after the mortal blow has been struck.
The Magic Council (ten of the greatest wizards alive) have a collective Oh Crap reaction when Siegrain spills Jellal's motivation for completing the Tower of Heaven: To resurrect Zeref, the most powerful and vicious dark wizard in history. Given that Zeref can easily create powerful demons like Deliora, their reaction seems justified. This fact convinces enough members of the Magic Council to vote in favor of firing the Etherion. They later have another such reaction when the Tower absorbs the Etherion, and they realize that "Siegrain" played them for fools.
Another Oh Crap incident during the Fighting Festival arc: Mirajane is watching fellow guild member Fried brutally torture her brother Elfman; she finally snaps and unlocks her most powerful magic, Take Over: Satan Soul. Another Oh Crap moment occured minutes later in the same fight when Mirajane busted out her S-Class lightning, water, and darkness magic to put Fried down.
During the S-Class Trial arc, one of the villains named Rustyrose has trounced Elfman and Evergreen with his magic, part of which is a pair of glasses that makes him immune to Evergreen's eye-based magic. After a Big Damn Heroes by Freed and Bickslow, Rustyrose also traps them in similar fashion. In a last ditch attempt, Bickslow attempts to use his own eye magic, which would let him control someone's body like a doll. Rustyrose simply mocks him, saying his glasses make him immune to such things. Then he realizes that he's not the target...
Twilight Ogre gets one after they realize that Makarov, Erza, and Mirajane are going to kick their asses for their bullying of Fairy Tail.
In Chapter 282, we have Natsu giving one to Sting, Rogue, Lector, and Frosh when he storms Sabertooth's lodgings and steamrolls over some of its nameless members. Rufus and Orga seem to get a more subdued version of this.
Too many to mention in Battle Royale, but an interesting example occurs right at the end when Shuuya refuses to shoot Kiriyama until he sees that look, saying "he's got to know it's coming" and "he's got tofeel it". A bit of a goose chase, since right up until his death Kiriyama is incapable of feeling anything at all.
Jo in Burst Angel ep "Eastern Angel, Western Hawk", when she discovers that "Ultra Beast" is yet another creature with the glowing brain she keeps running into. Made effective since she's normally The Stoic.
From D.Gray-Man, Kanda thinks that he's won his battle with Skinn Bolic, until Skinn stores enough energy inside of Kanda to materialize chains coming out of his chest which Skinn can use to drag him around, prevent him from using his swords, and electrocute him without missing. Oh Crap is Kanda's initial reaction, but Skinn didn't account for Kanda's Healing Factor and made the mistake of holding him right infront of him. Skinn has an Oh Crap face shortly after. Then after Kanda thinks that he's won, Skinn reveals himself to be still alive. Again, during the same battle, Skinn has destroyed Kanda's sword, only for Kanda to reveal that by sucking at his lifeforce, he can pull the pieces of his sword back together and cut Skinn cleanly in half with them, which he does. Oh Crap yet again.
In another battle, Allen has defeated Tyki Mikk by removing the Noah from him, only for Tyki to come back completely crazy, destroy any means of escaping, and reveal that he has a Superpowered Evil Side, which he cannot control and which only cares about killing them very violently. What made it rather ironic was that Allen triggered this power up by attempting to remove Tyki's Noah side.
Pretty much any case involving a Level 4 akuma requires an Oh Crap face.
Making it all the more awesome when a Level 4 attacks the HQ, kills lots of people and destroys most of it...and then it has to mess up Cross Marian's clothes. Cue Curb-Stomp Battle. The main reason for this scene is to show just how awesome Cross is.
The Fourteenth Noah is so scary that he scares a level 4 akuma when he appears and says "good morning".
Being a Dark Fantasy manga with elements of demonic horror taking place in one of the crappiest Crapsack Worlds this side of Warhammer, Berserk is chock full of this trope:
First notable moment was when Guts battled Nosferatu Zodd for the first time. He kept his cool for the first moments - until Zodd turns into his apostle form. The expression on Guts' face when Zodd transformed was one of pure gut-wrenching terror.
Then came the time when Guts was facing off against Wyald, his second encounter with an Apostle. He took it a lot better than with his fight with Zodd, but it was one of the few other times that we see Guts tremble with fear.
Wyald has a very satisfying one when Guts is about to "take his weapon away from him" and put a stop to his raping days for good, along with two in quick succession — the first when he realizes that Griffith does not have the Behelit, meaning he can't call on the Godhand to heal the wounds that Guts inflicted on him, and the second when he realizes that Zodd has shown up right behind him in full Apostle form. And is not happy with his shit.
The entire Eclipse ordeal is littered with Oh Crap moments for the good guys, one tragic expression after the other. It's basically a Mass "Oh, Crap!" convention.
The entire Band of the Hawk gets a collective one when they are transported to the Nexus where the Eclipse ceremony is held (a.k.a. Hell), and the realization of what the God Hand meant by "sacrifice" hits them.
Of particular note is the the look of absolute, unlimited and all-consuming horror on Guts' face when he realizes that Femto, a.k.a. GRIFFITH, is going to rape Casca, right in front of him.
And right along with this, Casca has this subtle, but nonetheless horrified look in her eyes when Femto kisses her that just about any survivor of sexual assault can relate to that says, "oh no. NO."
It's an anime trope, Pokémon has gotta be in somehow.
Team Rocket. With clockwork regularity.
In the very beginning of Pokémon: Destiny Deoxys, Rayquaza bursts out of the water that Deoxys had knocked it into and fires a Hyper Beam right in its face. Even despite its expressionless features, Deoxys was clearly shocked.
In the episode "Having a Wailord of a Time", Nurse Joy was keeping a Treecko, Torchic and Mudkip for a girl that was going to be a trainer. Unfortunately, the Torchic evolved into Combusken while Nurse Joy was away, leading to Ash and Max trying to hide it and substitute May's Torchic temporarily.
The unnamed Con Man gets one when he's trying to pawn off a Shiny Magikarp. He knocks on the door, and immediately starts selling. Only when he realizes that he knocked on Professor Oak's door does he realize his mistake.
From Pokémon: The First Movie, this is pretty much Dr. Fuji's reaction when staring an enraged Mewtwo in the face, knowing that the clone is going to reduce him to ashes. His last words are...
"We dreamed of creating the world's strongest Pokémon... and we succeeded."
At least she was smarter than Aqua Admin Ark, as he gloriously demonstrated in Round 212. It was smart of him to use Flannery as bait to lure Sapphire into an airtight cable car and lock the door behind her. It was also smart of him to flood the cable car with Azumarill and provide himself a way to breathe. And calling out Sharpedo to bite them to death seemed like a good idea at the time...NOT! Sapphire called out Rono (a Lairon at the time, which resists Bite) to break off its teeth, and he gloated at their inability to breathe throughout the whole ordeal - time better spent watching Sapphire as she used those teeth to cut a hole in the glass! It's a shame, as he could have won if he didn't try to rush Sapphire's demise, which wound up being his own downfall instead - in this case, Rono makes it literal, as he went flying to the next cable car down.
Sapphire: Did You Actually Believe? I had Rono break Sharpedo's teeth merely to defend myself? I was actually planning to use them for something else!
Also, Ruby's face when he realizes that Sapphire is the girl he saved from a Salamence (who he was also in love with) years before, and that the boy who she used to love was him. He manages to cover it up pretty well so no one notices. Sapphire does it as well later that chapter when he locks her in an aircar and she realizes the same thing he did as he shows her the scar he has from the Salamence attack.
Chiyo from Azumanga Daioh has a pretty epic one when she realized that Maaya the Iriomote Cat can eat animals as large as her dog, Tadakichi-san.
Chiyo has heaps.
The first time the Daedalus Maneuver was used on Macross/Robotech, it went right into the bridge of the Zentraedi ship. The look on the captain's face is pricelss.
Full Metal Panic!! The first time Sōsuke witnesses Gauron's Lambda Driver in operation.
Sōsuke: (shot is absorbed by az energy field) What in the—?! (gets blown back a few hundred meters by Gauron's shockwave)
Earlier, you could practically see him thinking "Oh Shit!" when he discovered the very large bomb planted on the hijacked plane carrying his classmates. (Keep in mind, Sōsuke's an expert when it comes to explosives. If he's making that kind of face it means things are really bad).
Another example from The Second Raid was the first episode where a tank commander really didn't expect the Arbalest to have a Lambda Driver.
And on a much larger scale for Sōsuke, he has this reaction whenever Kanameis angry.
Gates: YES!!! YES!!! YES!!! I'm getting closer! The only thing in front of me is one Arbalest on the verge of overheating! I'm gonna run you down and crush your little ass! YOU'RE TRAPPED LIKE A RAT, BOY!!! (jumps into a clearing just to find his target isn't there) Huh?! Hey! Where's my Arbalest?! (Mao, Kurz and Sōsuke step up and take aim) Aw, shit... Gates: (the 9.8-ton Arbalest jumps off from a billboard without scratching it, then the 10.8-ton Codarl chasing it lands on the same board which instantly flattens) No way, that's impossible!!
In Full Metal Panic!: The Second Raid OVA, the AS failed their dance routine and one of them crash into a wall, prompting a very shocked Melissa to open her mouth really wide. Tessa then inform her that the repairs will come out of her salary.
This occurs in the final confrontation between Jubei and Gemma in Ninja Scroll. Jubei's taken a pounding, had his arm broken (and probably a few ribs), and is lying on the ground, immobile, as Gemma stands over him, boasting his immortality. Jubei then proceeds to headbutt him.TO DEATH. The look on Gemma's face as Jubei smashes it into a bloody pulp is pure Oh Crap: you get the impression it's astonishment as much as pain that prevents him from fighting back. He got better.
Quite a few of Akagi's oppenents in Akagi have this on right after they play into his hands and lose.
Also happened to two of Hiei's foes in the Dark Tournament. In their round of the opening match, Zeru was sure he had incinerated Hiei. Then he got a wonderful Oh Crap face when Hiei revealed to have survived, and another immediately after when Hiei announced he was about to use the Ensatsu Kokuryuha (Zeru was disintegrated). Also in the second round of the final match, Bui had redirected Hiei's Kokuryuha against him, apparently disintegrating him, only for Hiei revealing himself not only unscathed but having just got a Mid-Season Upgrade exactly because he was hit by the Kokuryuha. Curb-Stomp Battle ensued.
Mom and Asagi share one when they realize Yotsuba just ran out into a typhoon.
Eyeshield 21, during the match against Seibu. After an onside kick with just a minute left on the clock, Monta and Tetsuma are in a catching battle. Because Monta has his hands on the grip of the ball, he overcomes Tetsuma. He starts running for a touchdown, but notices that the other team isn't doing anything. Tetsuma had landed with the ball before Monta could grab it away.
Don't forget one of the most Oh Crap faces in the series was in the same game against Seibu(at least in the manga version) when everyone thought that Deimon couldn't get enough points because they have no kicker AND the distance is far too wide. Of course, it just happened to be the moment Musashi decides to come back to the team. The face of Kid and seibus Caoch says it all.
In the final game of the manga, USA vs. Japan, Sena tries to blitz Clifford, the American quarterback who can also run at Light Speed (4.2 seconds in the 40 yard dash). He fails because they're the same speed, then Agon comes flying in from the other side. However, since Agon is even slower, Clifford dodges him too and now there are 2 zones open in the background. Que SHIN coming in out of nowhere, Trident Tackle at the ready. With nowhere to run, there's only one thing Clifford can do- pray for mercy.
In Asobi ni Iku yo! guy meets alien gal, guy's uncle pours her beer, guy takes beer from girl. Girl introduces herself and bows. Guy did the same and ends up with his face neer her boobs. His composture breaks and takes a sip.... of the beer, when he has zero alcohol resistance. Guy faints while saying "oh cra..."
The Excel♥Saga manga has Mince, who's been free of Excel trying to eat her for a pretty good period of time, encounter an amnesiac Excel. Mince's reaction covers a two-page spread.
Eudial from the third season gets three of these: the first one when the Holy Grail is formed, the second when Super Sailor Moon reflects her attack back at her with only one hand, and her final one occurs when she realizes Mimete has sabotaged her car's brakes and she's now heading for a cliff edge....
In the finale of School DaysMakoto gets a text message on his cell phone that just says "sorry", followed by lots of empty lines. He scrolls down to the end of the message where he finds just the word "sayounara." The background sounds stop, the picture jumps to a close up of the single word. Oh Crap.
He then is jumped by Sekai, one of his two Yandere girlfriends, with a knife and struggles to escape as he is stabbed to death.
A small gang of thugs (pretending to be the Dollars) surrounds Shizuo Heiwajima. When one of them figures out who they're fighting, he freaks out, rushes forward, and breaks his bat over Shizuo's head. Shizuo stumbles, and the thugs figure they've won...until they realize he's not moaning in pain, he's growling in rage.
Shizuo: "You aimed for my head. You've got to know that a blow like that can kill a guy, right? That means you were deliberately trying to kill me, right? That means whatever happens next...IS WHAT YOU DESERVE, RIGHT?"
I was (scary) so (scary) jealous of my disappointed self a moment ago. It (scary) would (scary) have (scary) been (scary) so much (scary) better (scary) if (scary scary) the man (scary scary) in front (scary) of me (scary scary scary) were (scary) indeed (scary scary) weak (scary scary scary scary scary scary scary HELP SCARY SCARY SCARY SCARY HELP SCARY SCARY HELP HELP HELP HELP I'M SCREWED HELP I'M SCREWED I'M SCREWD I'M SORRY I'M REALLY SORRY SORRY SORRY SORRY SORRY).
When Namie Yagiri was mocking Mikado, and suddenly the cellphones of everyone in the crowd start ringing
From Macross: Do You Remember Love?OH PROTOCULTURE!!!
In Macross Frontier: Grace O'Conner's face goes from Oh Crap to Oh Fuck right before she is shot dead by Alto.
In Soul Eater, Mosquito gets one when he realizes Arachnophobia has been deceived by Medusa, and that the real Brew is held by Death the Kid. Naturally, his beating the boy into a bloody mess has caused Brew to trigger a Defence Mechanism Superpower in Kid. That is, to start channelling his dad's power. And this after he'd taunted Kid for being a child death god.
Kyubey tells Madoka that her power is so great that if she makes a contract and becomes a Magical Girl, she could use her wish to rewrite reality. In the last episode, she takes him up on that and uses her wish to retcon Witches out of existence forever, past and future, forcing reality to rewrite the Magical Girl system. Kyubey's reaction is glorious.
Hao gets one in the finale of Shaman King. A priceless Oh Crap face when Yoh and Amidamaru slice him and his Spirit of Fire in half, just before they both explode. And he doesn't even say a word.
In Sonic X, Dr. Eggman gets a lot of Oh Crap moments quite often throughout both the first and second series, especially on moments when his plans have been or are about to be foiled, or when his Robots Of The Week have been or are about to be destroyed, like in Episode 13 when he realizes that his Guerra-Hard robot (E-18) is about to explode after being pummeled by Sonic with both of the Chaos Emeralds he snatched back from it in hand, and in Episode 58 when he, Decoe, Bocoe, and their Egg Octopus are about to be pummeled by Sonic.
Also, in Episode 9, Eggman's robot Serpenter destroys Amy's lucky bracelet that she had made for Sonic from the seashells she collected at the beach that she, Tails, and Cream were having fun at in the process of the Quizon coming together to form it. And Amy reacts to the destruction of her bracelet with a "This Cannot Be!" line. Not only does Amy cry over said destruction of her bracelet, she doesn't take that too well and has her Berserk Button pressed, hitting Eggman with a This Is Unforgivable and afterwards proceeding to kick both his and Serpenter's asses, and that's where Eggman gets an Oh Crap moment where he realizes that he shouldn't have made Amy this pissed off at him and that now that he has done so without knowing it anyway, he's completely and totally screwed.
In Episode 1 before that, Sam Speed, a hot-shot racer who loved being called the Highway Star or the Speed King due to his love of quick speed, got his own moment when he saw that Sonic was going even faster than him by using what he called a "Sonic Boom", which actually refers to him going even faster than his already insanely fast speed that he goes when he runs. Since then, he's gotten a lot better and become friendly rivals with Sonic in terms of racing speed.
Cowboy Bebop, Ballad of Fallen Angels. This exchange happens when Faye's captured at an opera, which cues an utterly terrified Oh Crap face from her:
This also gets turned around on Vicious later in the episode. He throws Spike out of a window; Spike throws a grenade back into the building as he falls.
Displayed by Twinkle, the leader of a group of eco-terrorists in "Gateway Shuffle" when she finds out that a receptacle that contained a sample of the virus they planned to use on Ganymede, which devolves humans exposed to it into monkeys, was planted on the ship by Spike... with said receptacle shattering inside their own ship, unleashing the virus.
From the anime's final episode: Knives has Vash in his line of sight for his Angel Arm cannonsactivated in both arms (and a blast from just one of those was enough to wipe out the entire city of July in the back-story). Knives is grinning like a loon, and Vash is sure he's done for. Then Vash hears the deceased Wolfwood's voice in his head telling him that "it" is right next to him. Vash then plunges his hand into the sand, bringing up the buried Cross Punisher gun he inherited from Wolfwood. Cue Knives' sudden facial change from psychotic confidence to "WTF?!"
Here's a clip of the entire fight sequence, with the above-mentioned moment starting around 5:30.
Tiger & Bunny has a great moment in the stinger for Episode 11 when Jake Martinez reveals that he knows about Origami Cyclone disguising himself as one of Jake's followers.
In Bakuman。, this is the typical reaction of any manga artist to getting canceled, although Aoki and Shiratori are relatively calm when receiving the news. Takahama briefly has a surprised facial expression, then sends his assistants home before cursing his luck alone.
Miura uses this phrase in his thoughts when seeing his immediate superior Aida come back depressed from a meeting in which two series from Aida’s group (Hideout Door, which Aida personally edits, and Detective Trap, which Miura edits) were up for cancellation, and hopes it’s only because Hideout Door, the lowest ranking series, was cancelled. He’s wrong; Detective Trap also got canceled.
During a heated argument between Mashiro and Miura over whether the Ashirogi pair should do gag manga or serious manga, with Miura’s reasoning being that gag manga aren’t as popular but more likely to stay for a long time, Miura lets his temper get the best of him and yells that Takagi should find another artist if Mashiro won’t do as he says. Takagi, his Berserk Button pressed, storms out while Miura gets an Oh Crap expression.
Early on, both Hattoris get this at once. Akira Hattori has this when the main characters show him drafts for a battle series, as he believes that they can eventually make a cult hit and that mainstream manga is a bad decision. Yujiro Hattori has one when he finds out that Eiji Nizuma has produced a chapter of Crow instead of for Yellow Hit, the series he had gotten serialized, and Yujiro worries that he's going to lose his job. In both cases, their worst fears are not realized; Mashiro and Takagi give up on battle manga, and the editor in chief approves Crow, which eventually becomes the top manga in Jump.
Hild of Ah! My Goddess fame seemed to have suffered a severe case of Badass Decay ever since her henchwoman Hagall overthrew her as ruler of Hell. Only a tiny fraction of her remained on Earth and she had to split off an even smaller piece to sneak back into Hell undetected...inside Keiichi's head. Now at this time she looked like a pint sized chibi girl, and seemed harmless. That is until Keiichi implanted this fraction into Hagall (by blowing into her ear!) and it promptly took full posession of her with impunity, forcing Hagall to release Hild's true form from imprisonment...said true form is a billion times more powerful, the owner of a lengendary DeathGlare and doesn't like rogue minions very much. Cue this trope being played for all it's worth and a nice Big "NO!" to boot.
Most enemies think this right before their defeat at the hands of Tsukune's harem (or Tsukune himself) in Rosario + Vampire.
In "Beyblade G-Revolution" Brooklyn gets his; when Kai unleashes his all in one last, ultimate, final attack and then realizes that, for the first time in his Beyblading career, he's going to lose.
The Bentenmaru's bridge crew have several of these during Episode 15 of Mouretsu Pirates. Due to events in the previous episode, they are stuck in quarantine and Marika has had to bring in the Hakuoh Academy Yacht Club to help her fly the ship in order to fulfill the conditions of her Letter of Marque. The crew are understandably worried about leaving the Bentenmaru in the yacht club's hands (especially after Luka, the psychic, suggests it might break down when they turn on the power), so they frantically try to write an instruction manual before the yacht club can cause any major damage, freaking out several times along the way.
Both crews have one when one of the yacht club members asks What Does This Button Do? and accidentally fires the Bentenmaru's main cannons.
After the manual is finished and the ship is underway, the crew breath a sigh of relief. Then Marika decides to do a practice FTL jump—something which they didn't put in the manual...
The entire city of Roanapur in Black Lagoon does this when they hear Roberta, the killer maid from hell, is coming back. Badder, angrier and crazier than ever.
In Chuunibyou Demo Koi ga Shitai!, it was Yuuta's expression when Touka shows him an audio clip of one of his "Dark Flame Master" delusions (which he considered as Old Shame and would want to get that rid of his system).
Psycho-Pass: The baddie has a knife to her friend's throat. Akane points her Dominator at him, only to be told "The Crime Coefficient is zero. Not a target for enforcement action. The trigger will be locked." Cue epicOh Crap from her, and from the audience too. It ends badly for her friend.
In Fate/Zero the Assassins get a magnificent one in this scene, when Rider finishes his "The Reason You Suck" Speech to Saber and reveals he didn't forget he was in the process of sicking his Badass Army on them. Already good because Rider had annihilated their two advantages (superior numbers and ability to hide: there was nowhere to hide, and Rider's Badass Army numbered in the thousands), it becomes magnificent due the Assassins wearing expressionless masks and still showing their utter fear.
In Sangatsu No Lion, Rei becomes shocked and almost has a breakdown the moment he realizes that his underestimation of Shimada's skill during their first official shogi match lead him to an unwinnable situation early on during the game before he fully realized it. Shimada clears his throat to snap him out of it.