Played with in Cheeky Angel, where the school bad boy wears a black shirt, against code, because he gets in a ton of fights and blood won't show on black.
In Japan, red is the traditional color of the hero. Many of these heroes fit the red formula in the Red Oni, Blue Oni duo, as well as highlighting their usual fiery spirit.
Alucard of Hellsing and Vash of Trigun both practically personify the trope; although in the case of Trigun, Wolfwood doesn't fare much better in his black suit and white shirt. Hell, Alucard has the primary battle tactic of letting his opponent tear him to shreds.
Inuyasha: In his completely red outfit, Inuyasha is not particularly lucky, and despite (because of?) his demonic resilience, Kagome practically has to duct tape him back together after many battles, including once having a punch go through his abdomen and out the other side. His brother, Sesshomaru, provoked the mutilation gods merely by having a few red stripes on his clothing, and subsequently lost an arm. The censor potential is especially notable here, as blood seems darker on dark-suited folks. In fact, the movies have less strict censorship rules than the anime, and the blood is red rather than mostly black, so his injuries seem less stark than in the regular series. In certain cases, it's actually difficult to tell if he's been injured or not. You know, except ongeneralprinciples.
Ranma Ĺ: The same goes for the titular character in Takahashi's previous work in a red shirt, Ranma Saotome, but in a more comedic manner.
In the climax of the Kurosawa-based Samurai 7, Kyuzo's violent, extremely ironic death was probably the result of his signature crimson Badass Longcoat.
Van from Vision of Escaflowne fits this trope to a T. Look no further than episode 14 as an example.
Chrono from Chrono Crusade wears a red coat and red shorts, and true to the trope, he's constantly getting injured, particularly in the manga. In the manga, he loses one of his arms at least three times. (Of course, as a demon, he has the power to heal his wounds...which is part of the reason why he feels like he can put himself in so much danger.)
Asuka in Neon Genesis Evangelion wears a red plugsuit and has red hair. She is the one that gets the most severe injuries out of all of the pilots. Asuka gets to feel the pain of being impaled through the eye, eaten alive, arm cut in half, and finally impaled through her arm, head (again), and torso with 9 spears, all at 300% strength (her sync rate of 300 made her feel everything three times stronger than reality.)
The same goes for her red mech, Unit 02, which, in one battle, had both arms and its head cut off, while, in The Movie, it was wrecked up in a manner so graphic it's only rivaled by the destruction of Unit 03, piloted by Toji.
It's implied that Asuka's sync rate is so high in End of Evangelion that anything that happens to her Eva actually physically happens to her as well. As seen when her arm seemingly spontaneously splits in half just as her Eva is speared by the MP Evas.
The trope also applies to Misato, who wears a red jacket and is the only main character to be killed in the JSSDF's raid in End of Evangelion, as she is fatally shot, and, before she can succumb from her injuries, blown up.
Shanks depending on who does the coloring, has either a red or black cape. Subverted as he threw it off to swim out to save Luffy, and then lost his arm.
Luffy fits too, with his standard red shirt. And boy, does he get beat up.
Ed from Fullmetal Alchemist has his standard red duster. On the evening before the final battle, he purchases a bunch of red fabric and replaces it because his old one got torn up after he went north. His reasons for wearing red is that red is a Badass color or he reckons it psyches his mind. It doesn't do much to hide wounds, though, seeing as almost every time he's in a major fight, at least part of his shirt comes off.
Kenshin wears a red kimono (and pretty much only that one kimono) throughout the series. However, he's portrayed as wearing blue in flashbacks when he was an assassin.
Sanosuke wears an iconic red headband. Unsurprisingly, he gets a lot of head injuries whether by being punched in the head or head-butting someone else.
In Black Butler, Madam Red not only wears a red cloak, but the colour red makes up her a major part of her backstory. So does Grell while in shinigami form and it is a major part of her character as well. After Madam Red's death, she even takes the cloak from her, saying "You're not fit to wear the color red."
Ban from Nanatsu No Taizai is an immortal that is often subjugated to all sorts of bloody wounds that he can just simply heal from. Fittingly, his standard attire is predominately red.
Deadpool - Deadpool has "always been partial to red and black" and his uniform is primarily red with black accents.
In an interesting color inversion, Nausicaa (of Nausicaš of the Valley of the Wind) goes into the last part of the movie wearing a red dress, which is then dyed blue from being soaked in blue Ohmu blood.
Rebel Without a Cause: Jim wears the iconic red jacket for most of the film, but lends it to Plato shortly before the latter is killed. When Jim's father arrives on the scene, he recognizes the jacket and thinks it's his son who's been shot.
Ultraviolet: when the titular character receives a gash on her hand, her colour-changing clothes immediately change to red.
In Hero, the most violent version of the story uses red as the main colour.
In Schindler's List, a little girl in a red jacketnote Who really stands out since the rest of the movie is in black and white (except the beginning, and the ending). is seen at the ghetto. Later in the movie, Schindler sees her corpse about to be burned.
In the Silent Hill movie, Rose's outfit starts out in light spring colors, fading to duller and duller shades throughout the movie, then turning blood red for the climax.
In Terry Goodkind's Sword of Truth series, the Mord-Sith are female torturer/bodyguards who have color coded outfits. Usually, they wear plain brown leather. When they switch to a red outfit, that's when they mean business. They also have a white outfit, which symbolizes when a Mord-Sith has "trained" (read: tortured and broken) her pet so well that she doesn't need to coerce him into anything. This particular outfit shows up twice; once in the first book, where the main character is the pet, and once in the last book, when one of the Mord-Sith gets married. Either Goodkind was just going for a white outfit or he was trying to say something...
In Hero by Perry Moore, Ruth is stabbed through the stomach - BY A TREE BRANCH - but it takes Thom and Scarlett a minute to figure out that she's dying, thanks to her red dress.
A young Richard Bolitho (from the novels by Alexander Kent) wonders why his captain wears a red coat before a battle. Needless to say, he finds out.
One of the children's spinoff books based on Cluedo had Miss Scarlet being identified for an accidental stabbing because she was the only one who had clothes she could use to wipe the blood off her knife.
Occurs in Witch by Christopher Pike. Julia has a vision of Jim dying in a gas station, and his red jacket is very prominent in the vision.
The Eastern Empire from the later Heralds of Valdemar books issues dull red uniforms to its army. The joke in that army is that the color was chosen to cut down on cleaning bills post-battle.
Averted by the Bards of Valdemar, who also wear red uniforms. Thanks to their Bardic Immunity, it's against the law to harm them, and the relatively few major Bard characters tend to avoid suffering the same degree of trauma that other characters - including the white-clad Heralds - are prone to.
In a subversion, Anita Blake prefers black clothes while working, because she finds that black hides the blood even better than red.
In Cerberon, Aladavan is wearing a red jacket when he's nearly disemboweled by a skraad. He comments on this fact and is amazed that his white trousers didn't get bloody.
Mal Reynolds of Firefly wears mostly earth tones, including brown and red. These clothes are frequently ripped and torn, mostly by bullets and knives. Occasionally, this color scheme is the direct cause of some of Mal's injuries — like when he wears it into an Alliance-friendly bar on Unification Day and picks a fight. Mal wearing red is played with in the side comic book story Serenity: Those Left Behind. In the comic, River comments that she hates the color red on Mal, which is an ironic throwback to the episode "Ariel" in which she cuts Jayne with a butcher knife and then comments that he looks better in red. River's comment is very likely intended to suggest that Mal does this trope on purpose for the reason given in the page quote. River may or may not like Jayne, but definitely didn't like the Blue Sun shirt he was wearing, and slashing him was the best way she came up with to get him and the shirt to go away.
The miniseries adaptation of Tony Kushner's Angels In America puts long-suffering AIDS patient Prior in a red robe when he goes to Heaven, with a stylistic nod to Schindler's List thrown in by having the red robe the only thing in color through that part of the sequence.
In Heroes, Claire Bennett's season one cheerleading uniform was mostly red, for good reason.
In Legend of the Seeker (see Sword of Truth), the Mord-Sith only wore the red version of their outfit at first, with no explanation given, but an episode in the second season finally showed off the white leather, along with an explanation of what it meant.
In Degrassi, Campbell wears a red team sweatshirt on the day he commits suicide.
The Spanish Civil War song "Tengo la camisa roja" ("I have my shirt in red"), in which a soldier tells others that he's covered in the blood of his deceased partner.
Dante of the Devil May Cry series wears a Badass Longcoat of an almost garishly blood-crimson color. He does have a tendency to suffer atrocious levels of injury — often with his own weaponry — but it almost never slows him down for long. Part of this is due to Cutscene Power to the Max, wherein Dante is a practically unkillable warrior, and the other part is due to his demonic heritage.
The Red Mages. Though they usually are less of Squishy Wizards than Black or White ones due to being able to equip better gear.
Final Fantasy IX Freya Crescent is also dressed in red, though she's a Dragoon rather than a Red Mage. Something of an aversion, since Freya's Jump ability means she tends to avoid getting hurt. Except emotionally of course, but then this is FinalFantasy IX we're talking about.
Auron in Final Fantasy X seems like an exception, in that his blood-red longcoat doesn't accompany any particular hardship in the quest. But then, he's already dead to begin with.
Ditto for Vincent Valentine in Dirge of Cerberus - when he sustains a major wound, it closes up right away.
Lemon, the "Red Baron" from Shining Force 2, wears a deep red suit of armor. It is rumored that the red color comes from the blood of all the enemies he has slain. When he is turned into a vampire, he attempts to kill himself in several ways (because Who Wants to Live Forever?).
In Tales of Symphonia, the party goes to the king of Tethe'alla to discuss the present situation. After making their case, they are sent to the "Crimson Room", where they keep visitors they're not sure what to do with. The implication is that should they decide to kill said guests, the all-red decor in the room will hide the bloodstains better.
In Shadow Hearts: From the New World, Killer, who sports red pants and hair, seems to sustain near-fatal injuries on a regular basis. Interestingly enough, he actually does die after the boss fight in which he transforms into an all-red dragon.
Sissel from Ghost Trick wears a red suit, and starts off dead. However, it gets a bit complicated as in reality, Sissel mistook the corpse of his owner, Yomiel, for his own and is actually a black cat wearing a red neckerchief. Yomiel meanwhile, was 'killed' ten year prior by a fragment of the Temsik meteorite, and as a result cannot feel pain, or be killed, meaning that he can get shot and slapped around a fair bit with no actual damage.
Not characters, but ships: In RefleX, both the Phoenix and the (human-made Virgo) are red-colored. Both ships are totaled in Area 7. The latter's pilot manages to escape somehow. Unfortunately, the former's pilot dies...although said ship then comes back controlled by an AI and beats the shit out of the boss that murdered it.
The school uniform in Kanon is red. Mai, the Emotionless Girl that swordfights with demons, sustains life-threatening injuries in her uniform, with accompanying red stains. However, in the ball scene, where nobody is wearing red, people are fiercely attacked and, in some cases, badly hurt, but nobody bleeds. In the SUV scene, the victim isn't even shown, and replaced in the remake with the red stain of a strawberry dropped on the ground.
Fate/stay night - Rin Tohsaka wears red in all of her outfits (except her sleepclothes), but it's pretty much a subversion, because the one time you see her seriously wounded, her blood isn't just on her, it's everywhere.
Late in the fourth act of Homestuck, an alternate future version of resident Bad Ass Dave Strider is found dead in a red tuxedo. Earlier on, in the Midnight Crew Intermission, this is inverted: the antagonists, a pool-themed Gang of Hats called The Felt, are dressed in entriely in green and have green skin. The blood is quite vividly noticeable.
Daisy also uses red to her advantage, however — the red ascot she wears as part of her uniform is because she wants to hide Jigsaw's vampire bites, and she even hides a vial of Jigsaw's vampire blood inside her hairdo — did we mention she's a redhead? — to keep herself alive after said shooting from Jason.
Even before the Romans, the Spartan army dressed in crimson, supposedly because crimson garments were seen as bearing "the least resemblance to women's clothing."
The Knights Hospitaller, or Knights of St. John. Their field uniform was (and still is) a red surcoat with a large white Maltese cross. The red surcoat may be worn only at the combat zone; elsewhere, a black surcoat with white Maltese cross is to be worn.
The British army from the 17th to 19th century were famously known as "redcoats" due to their uniform. The common belief was that this was to hide blood stains. Other theories for why the colour was used are:
The bright colours were simply to enable a soldier to distinguish friend and foe easily in the heat of battle. (Which has both benefits and drawbacks.)
The use of red for the majority of infantry dates back to England's New Model Army in 1645, though some units used it beforehand. Some sources have it that Cromwell wanted blue, but red was cheaper and/or the only colour available in the quantities needed. Interestingly, because of this use of cheap natural dyes, the average soldier's field uniform would rapidly fade to a muddy maroon shade rather than the 'factory fresh' red inevitably seen in fiction.
The colloquialism "redcoat" only dates back to the 19th century; they were called "the King's men" by the American rebels.
One of the more widely accepted theories among historians (who, it should be noted, scoff at the aforementioned blood stain theory) comes from the fact that during most of this period, the British army was world-renowned for being one of the best and most well-trained armies in the world. Since the range and accuracy of muskets at the time rendered stealth and modern guerrilla-like tactics meaningless, there was little reason not to flaunt your reputation to intimidate your opponents.
Unfortunately, the red dye and the fabric used was of abysmal quality, so after a few months in the field the English would look bizarre: the red jackets would have run, leaving them a kind of anemic pink, whilst the dye would have stained the white breeches, making it look like the soldiers had wet themselves whilst pissing blood (for which reason most soldiers in the field tried to source new attire; cavalry breeches were preferred), and added to all that there would be the various scraps of cloth used to patch uniforms.
Napoleon wore a red shirt in battle, supposedly to never let the enemy see him bleed.
According to that other wiki, Confederate general A. P. Hill had a red "battle shirt". He was never seriously injured so long as he wore the red plaid shirt, making it a subversion of Bring My Red Jacket and Red Shirt, as well as being a combination of Contractual Immortality and The Lady's Favour, since it was given to him by his wife, who said "As long as you wear this, you'll come home to me.". He died the only time he didn't wear it into battle, at Petersburg.
Giuseppe Garibaldi, an important player in the unification of Italy in the 19th century, led redshirts (not that kind) to battle. Some legends say he was inspired by butchers using the blood-hiding aspect, but The Other Wiki notes this is unlikely.
Similarly, the gun decks of men of war in the Age of Sail were customarily painted red to lessen the shock of seeing the copious amounts of blood that covered them in battle. It was also cheap.
Yamagata Masakage, one of the Takeda clan's 24 generals, was known for his men's red armor. The Takeda cavalry was known throughout Japan during the Sengoku era as being the finest.
In sports, red shirts are a popular choice. In football/soccer, at least two teams are nicknamed "Red Devils" (Manchester United and Belgium); England has it as secondary uniform, and since their only FIFA World Cup was won with a red kit, it's used for special occasions; and in a not-very-successful attempt, Germany used red for 4 years as a secondary kit in an attempt to intimidate (it has since been changed to black). Conversely, in college American football, to be a 'redshirt' means to be put on the practice squad for a year. The reason for this is to get better while retaining a year of eligibility of play.
Redcaps were named for their red caps. The red came from the blood of people they killed, which they did often, since the red would eventually fade.
On U.S. aircraft carriers, flight deck crew wear different colors to denote their jobs. Those wearing red shirts handle ordnance.
Which also brings to mind the other Red Shirts as well, since anything ordinance related is on their shoulders. Ergo, in the event of fire, part of their task is to get rid of any ordinance on the flight/hanger deck, and dump them overboard while other members of the crew spray the plane down with water and foam. If the ordinance detonates before they can get it away safely, they're the first to buy the farm... but within a few microseconds so is everyone else in the blast radius.
At least one Japanese commander in World War II was on record for wearing a red shirt specifically to hide any wounds he might sustain on the field, lest his men become demoralized by the sight of their commander bleeding to death.
In revolutionary France, it was recommended that a guillotine be painted red, so as to make the sight of a person being beheaded slightly less gruesome.
As freshly-shed human blood actually comes in two shades, bright scarlet for oxygenated and reddish-maroon for deoxygenated, it's questionable how well a wounded person's blood would actually blend in with any given shade of red fabric. Once it dries, of course, it'll turn brownish and stand out anyway.