Belarus as well, to the point of attacking Denmark for making a small comment about how he'd win the costume contest because it implied that he thought he could beat her darling Russia.
England definitely counts, too. This becomes more apparent when France or America is around.
Germany is very tightly wound, and responds by either screaming at and/or threatening the problem until it backs down.
Tsukihi Araragi from Bakemonogatari, to the point where her brother describes her as having hysteria.
Grineed from Beet the Vandel Buster goes berserk when he's addressed in a casual manner. "Dude, calm down" will make him blow a crater in the ground with the sheer force of his trembling with rage. He constantly soaks himself in sedative resin, because he knows that sort of thing is "Not OK", no matter who you are.
If you so much as blink around Revy in Black Lagoon, odds are she'll get pissed off enough to fill you with holes.
Mayuri Kurotsuchi, the unhinged Mad Scientist, has something of a hair-trigger temper. This was extremely prevalent in his early appearances, where he flew off the handle at the most minute of provocations, which he often took out on his daughter. He has chilled out significantly since then, however, and while he is still callous and easily annoyed, he handles it a lot better. The running joke in the fandom is that Ichigo's group broke into Soul Society on one of Mayuri's bad days. This is made even funnier later on when Mayuri offers only a complaint when Ichigo dares refer to him without rank or honorifics: the other captains comment that Mayuri must be in an excellent mood to let Ichigo off so lightly. Mayuri's good mood does promptly vanish a short while later when Ichigo compares him to Urahara. Even a good day can't stop Mayuri's temper triggering to that accusation.
Kensei Muguruma's personality. When first meeting the Vizards, Orihime nervously asked where the bathroom was. Love and Lisa had to restrain him from hurting her out of pure irritation. His method for comforting a child almost killed by hollows was "Smile, dammit!". For extra humor, he is stuck with a lieutenant who happens to be The Ditz meets Manchild, who flits between Genki Girl and Hair-Trigger Temper herself, over the most minor things (such as sesame-topped rice balls).
Hiyori Sarugaki hates everyone and takes offense at nearly anything the other characters say to her. She even once jump-kicked Shinji for literally no reason before telling him that she wasn't going to apologize.
Byakuya Kuchiki is revealed to have had one in his youth. His grandfather commented that he needed to learn how to control the temper before he could develop his talent. As an adult, he acts like The Stoic but there are very strong hints that he's merely become extremely good at hiding the fact he's still got a short temper.
Classi9 has Wagner, who's in a constant state of annoyance, especially when around Haydn or Tchaikovsky. He gets really angry for no reason and even makes himself mad when he comes to slightly unfortunate realizations. He also never explains what makes him so angry, which lead Beethoven to think he had done something terrible and that their bond was unsalvageable when Wagner was actually mad at himself for not being able to beat him.
Bulma: Hey, creep! Were the first two losses not enough? How'd you come back to life, anyways? You're not just obsessed with revenge, you suck at it!
Nappa continuously loses his cool while fighting Gohan, Krillin, and Piccolo, and against Goku, he just explodes. Seriously, he makes Vegeta look rational in comparison.
Majin Buu, having about the intelligence and temperament of a child, would easily get set off and go on rampages until whatever annoyed him is dead and burned to a crisp. Even after he gains a certain amount of intelligence as Super Buu, he is still prone to temper tantrums when things don't go his way even slightly. He does calm down after his evil side is killed and he begins living among the heroes; while he still gets mad easily, it's shown that Mr. Satan is scolding him about his temper, so he's making an effort to keep it in check.
In Dragon Ball Z: Battle of Gods, most of the threat Beerus provides in the combination of his incomprehensible power and extremely short fuse. He authorized the destruction of planet Vegeta because King Vegeta only gave him the second-comfiest pillow, and nearly blew up the Earth because Majin Buu wouldn't share his pudding cup with him.
Shizuo Heiwajima of Durarara!! has a hair-trigger temper and monstrous strength to go along with it. However, he's aware and ashamed of his violent habits and wants to get "strong enough" to keep a lid on them. There's one scene where hearing that someone has been harassing his friend Celty, he starts muttering "Kill them kill them kill them kill them..." Celty tells him to try to calm down, and Shizuo responds that he is: he hopes that by muttering those words it will release enough of his anger that he won't actually go and kill them.
In Endride, Ibelda is quick to take offense, even among comrades. He quickly evolves into an Axe-CrazyBlood Knight as time goes on, slaughtering his teammates and his employer, the King.
Daigo Ikari from Eyeshield 21 will always get angry when someone mentions Ojou High School or its football team, the White Knights, in a bad light; the problem is that every time he hears anything, he's always quick to assume the worst.
This leads to a running gag that Ikari never actually gets to play in a game until the second time Ojou plays Daimon, at least a dozen games into their season. The reason is that he always attacks someone and gets himself ejected before the game even starts. His teammates try to prevent this by binding him with chains. It doesn't work.
A giveaway is the fact that his surname is a homophone for the Japanese word for anger.
Hiro Sohma from Fruits Basket is a particularly obnoxious version, made even more irritating by his monotone delivery. Gullible Tohru falls over herself trying to appease him, while most viewers quietly harbor a desire to hit the little brat with something heavy. Unless, of course, you find it refreshing that Somebody Doesn't Love Raymond.
Kyo is like this early on in the manga/anime, particularly towards Tohru and Yuki, but he calms down as the series goes on.
"Black Haru", laid-back Hatsuharu Sohma's hostile split personality, has shown signs of this trope as well, deliberately misconstruing Tohru and the student council's president (though the latter probably deserved it).
Sousuke from Full Metal Panic! can get this way towards people, mostly if it seems to him like the person is "threatening the wellbeing of" Kaname. Even the most mundane, normal things that people say or do can be misconstrued by him as being a dangerous "threat" that must be eliminated. Justified in that he was raised by the KGB, with a highly suspicious, Crazy Survivalist nature.
Cross Marian of D.Gray-Man may fit somewhat. It seems he can be very cool and composed if need be. But there are times when he's prone to showing a bit of a violent temper. Such as him having to nurse Allen back to health. Allen is unresponsive, thus Cross has to cook for him, feed him, and do his laundry. Cross' response to Allen not eating is kicking in a table and creaming. He washes the laundry with his feet and stomps hard enough to crack the wash tub. Ba Ba tries to warn him, but Cross ignores him and continues stomping. He gets furious with Allen in a back-story novel, D.Gray-Man Reverse, and in response to his rage, he punches Allen in the face and pulls his gun on him. Tim hits him to stop him from shooting. He has an important meeting with Allen and drops some very distressing news on him. Allen is frozen in shock for a minute, and Cross, frustrated at Allen's unresponsiveness, responds by slapping him hard enough to knock him to the floor. Later in the meeting, Allen becomes angered by Cross' parting words. He tries to get Cross to wait, then resorts to throwing Tim and hitting him. Cross seethes in anger, then goes to attack Allen, with a Crow guard holding him back.
Eiri Yuki from Gravitation has this sort of temper with boyfriend Shuichi whenever he's trying to mess with the guy's head. In a slight subversion, however, Shuichi catches on to this ploy pretty quickly. That's not to say that he's any good at defending against it though.
In Guardian Fairy Michel, it doesn't take much to make Salome angry, whether it's her minions annoying her or a slight delay in her search for treasure. Her default mood when not smug is to angrily shout when something goes wrong.
Inuyasha: Inuyasha and Sesshoumaru are far more Not So Different than either of them will admit. This includes the short fuse that lights their tempers. Inuyasha is openly grumpy, with a base state of "mildly irritated". This flares up into angry on a regular basis even over trivial things. Sesshoumaru, on the other hand, will flit between The Stoic and Tranquil Fury, although it would be a mistake to think his temper is more muted than Inuyasha since Sesshoumaru's anger tends to be more lethal than Inuyasha's. Toutousai once lampshades this by observing that their identical short tempers makes it very easy to see that they're brothers.
Shinobu of Junjou Romantica often misinterprets even the slightest of things and becomes irrationally angry over them. The fact that he knows he's smarter than everyone else only makes this more apparent.
Tomoe from Kamisama Kiss is in many ways an Expy of InuYasha and like him Tomoe is openly grumpy all the time, has a face that always seems to be set to a "mildly irritated" expression and he tends to go ballistic over minor things.
Naru and Motoko from Love Hina start off with this trope, going Up to Eleven in the anime, though this happens less often once Keitaro manages to eventually win them over.
My Hero Academia has KatsukiBakugo, who has an explosive temper matching his Quirk; he frequently yells at people to "DIE!!" - including when brushing his teeth.Character Development has shown him a little calmer and more mature since the series beginning, but he's still an angry, angry young man.
Sakura can get like this at times due to her fiery Tsundere persona.
Tsunade will think nothing of pounding your face in if she gets pissed off.
Kakuzu is stated to have one, although it's more of an Informed Flaw
Mio from Nichijou has a tendency to get angry a lot quicker than usual whenever Yuuko or her sister, Yoshino, are around, due to the former's idiocy and the latter being The Gadfly. When shegetsangry...
Buggy the Clown is an interesting variation, where there is only one thing that sets him off: Mentioning his red nose. However, he seems to be a bit hard of hearing and tends to interpret anything you say as an insult to his nose, meaning he effectively has a Hair-Trigger Temper.
Eustass Kid, to a degree than anything that so much as irritates him can set him off. His Ax-Crazy disposition is balanced out by his far more level-headed subordinate Killer.
Jack "the Drought" is essentially impossible to negotiate with because of his temper combined with a permanent desire for destruction; the moment anything stops going exactly as planned, such as someone even asking for a chance to talk things out, is the moment he starts getting very, very violent.
Misty, while usually nice, had no patience for Ash's stupidity, especially in the pre-Togepi episodes.
Ash himself had such a temper in the Kanto episodes, such as throwing a tantrum and chasing Mankey up a tree when it stole his hat in "Primeape Goes Bananas" and would frequently bicker with Misty. He became calmer since then.
The episode "The Song of Jigglypuff" has an entire town full of these, to the point that one Officer Jenny (who herself seems a little on edge) has to go around town breaking up fights. This is because nobody there gets enough sleep (being the Pokémon equivalent of Las Vegas and all).
In Pop Team Epic: Popuko's only real consistent personality trait is her tendency to get inordinately angry at relatively innocuous things. She's been thrown into a swearing, violent rage by such things as thunder, being asked her name, seeing a cuckoo clock, and being asked whether she wants beef or chicken for her meal.
Akane Tendo from Ranma ½ can sometimes come off as this around Ranma Saotome, mainly in the earlier parts of the anime and manga.
Slayers: Lina, Lina, Lina... insult her appearance (namely her small bustline), deny her food or money, spill her food, upstage her - any of these warrants either some sort of explosion, screaming, or physical harm. Two egregious examples are Lina nearly drowning Amelia in a hot spring after Amelia makes a lighthearted joke about growing her bustline, and Lina nuking an entire restaurant for the owner accidentally stepping on a sardine she was eating (which she didn't want in the first place) in the Cold Open of Slayers Premium. While she has always had a short temper, though, later anime productions flanderize it.
Manabizaki, the main character of SWOT, always seems angry and annoyed. He gets pissed at anything he deems which interrupts his study time (which happens a lot) and has a tendency to fly into a rage at the slightest provocation. The fact that his school is filled with delinquents doesn't help.
The Nitro from Toriko are one of the more dangerous species in the setting, which is a bonafide Death World, because of an unholy combination of vast strength, intelligence, voracity, and very short and violent tempers. They were called "Nitro" because they have temperaments akin to nitroglycerine. Even the Taste Hermit Chichi, a presumably friendly Nitro who is able and willing to speak to humans, has a pretty short temper.
Shinobu from Urusei Yatsura used to be a nice and calm teenage girl. But because of all the wackiness after Lum showed up and stole her boyfriend Ataru, the littlest actions around her can suddenly send her into a blinding rage, which is made worse by the massive strength upgrade that goes with it.