Chest Insignia

The universal formula for depicting a character to be instantly recognizable as "a superhero" of some sort: put them in reasonably form-fitting clothes, and then add a prominent symbol on the chest.

Almost universally in the earlier eras, and in many cases today, the logo is centered and covers at least half the space available; a variant, that appears more and more frequently nowadays, has it shrunk down and over the heart like a police badge, or on a belt buckle. Copyright-holders soon realized that these insignia were marketing gold, in that fans of the characters were more consistently attracted to the insignia than the faces of the characters themselves; a valuable realization when different performers were chosen to portray the characters for various reasons. In addition, it's often easier to slap a stylized letter or icon onto merchandise, since the Uncanny Valley comes into play when trying to incorporate character faces onto merchandise.

Recently there has been a trend (particularly with less "super" characters) of justifying the symbol by having it attract gunfire towards the torso (which is easier to armour), such as with Batman and The Punisher.

Said symbol will often be Brought to You By The Letter S. If it glows, there's overlap with Heart Light.

Compare Highly Conspicuous Uniform (the military version of this trope), Symbol Motif Clothing.

Anime & Manga

 * Science Ninja Team Gatchaman. All the team members have a stylized bird chest symbol on their costumes.
 * Pretty Cure in Yes! Precure 5 have butterflies on their chests.
 * These resemble (seemingly by design) the bows often seen on the chests of other Magical Girls, including their predecessors in the two previous Pretty Cure continuities (as well as some others you might have heard of). Not quite a Chest Insignia, and not a reliable indicator by any stretch, but if you're the Monster of the Week and you meet a girl in with a bow on her chest, you should probably flee.
 * The hiragana character "bu" (ぶ) in Ai to Yuuki no Pig Girl Tonde Buurin.
 * Every Navi in Megaman Battle Network has a circular personal symbol of some sort, and several mount it in the center of their chests, notably Rockman himself. (Hino "Hinoken" Kenichi actually used recolors of the same symbol for all three of the Navis he operated during the series: Fireman, Heatman, and Flameman.)
 * There's a subversion with Blood Knight Bass/Forte: in place of a symbol he has a massive scar where his symbol would normally be.

Comics -- The DCU

 * Superman's "S" shield, shared by various sidekicks, and parodied repeatedly throughout pop culture.
 * His wacky duplicate Bizarro, on the other hand, has a backwards "S" shield that looks almost like a "Z" -- and a backwards spitcurl to boot.
 * In Superman/Fantastic 4, Johnny Storm attempts to recruit Superman by offering, "It doesn't take much to make that 'S' into a '5'."
 * The symbol has varied in different incarnations. Currently the Golden Age Superman is shown with a bloated looking "S". Kingdom Come Superman had a more angular stylized "S".
 * In Smallville Clark gets this scorched onto his chest.
 * Zibarro, the "imperfect" duplicate of Bizarro in All Star Superman has a "Z" instead of a backwards "S". At the end of the story the D.N.A. P.R.O.J.E.C.T. has.
 * Batman's bat silhouette. This was lampshaded in The Dark Knight Returns, where Batman admits that the famous bright yellow background is, obviously, a great big target. He then goes on to explain that he did it because he "can't armor my head".
 * Some of the Silver Age stories have the bat-emblem used as a diamond-edged cutting tool.
 * And Robin's off-center "R" in a circle.
 * The similarity of the original version to the registered trademark symbol ® has been a frequent parody gag.
 * The Batgirls also have batsymbols on their chests, although Cassandra Cain's is more of an outline.
 * As does the current Batwoman. The original Bat-Woman and Bat-Girl didn't, though.
 * Green Lantern's namesake -- more stylized for the Silver Age Green Lantern Corps than for Golden Age's Alan Scott.
 * With the formation of more Lantern Corps, each of them have their own insignia.
 * This is done for maximum horrific effect in Blackest Night among the Black Lanterns. When a corpse rises as a Black Lantern, the Black Hand symbol (a downward-pointing triangle with five lines coming from the top) is always incorporated into their new costume; sometimes in extremely imaginative ways (for instance, Black Lantern Superman has his S-shield as the triangle).
 * Both the various incarnations of the Flash and the Shazam "Marvel Family" use a lightning bolt insignia.
 * The Tasmanian Devil puts an interesting spin on this, as the character transforms into a werebeast form. When he does this, red fur grows over his entire body... except for a white patch on his chest forming the letter "T".
 * In JSA: Classified #2, Power Girl explains her distinctive (arguably infamous) costume "keyhole" as a kind of anti-insignia: "The first time I made this costume, I wanted to have a symbol, like you. I just... I couldn't think of anything. I thought eventually, I'd figure it out. And close the hole. But I haven't."
 * Leading to the infamous "Fill my hole, Superman."
 * Ironically, the original reason was just that Power Girl was an aggressive woman who took pride in her femininity.
 * She also categorically refused a P insignia offer by a JSA teammate.
 * The lack of an insignia became an unintentional bit of Fridge Brilliance. Her "cleavage window" is the same kind of circle with a line that's used as the 'Power' icon for most electronics.
 * The Golden Age Crimson Avenger, after he abandoned his Civvie Spandex, wore a costume with a sunburst on the chest. The modern Crimson Avenger claims this was a stylized bullet hole; her own Civvie Spandex has a realistic blood-splatter.
 * Both Liberty Belles wear an image of, surprise surprise, the Liberty Bell. Johnny Quick (husband of the first and father of the second), had a pair of wings on his costume.
 * The reboot version of Lar Gand of the Legion of Super-Heroes wore a costume with an insignia that could be seen as either an "M" for M'onel (his 30th century Code Name) or "V" for Valor (his 20th century one). Various other Legionnaires also wear or have worn chest insignias, such as Sun Boy's sunburst and Timber Wolf's stylized wolf head.
 * By the post-Zero Hour continuity, if not before, it became standard for all Legionnaires to wear a belt buckle with the Legion's insignia, an L and star inside a circle.
 * Wonder Woman, for most of her history, has had a soaring eagle on the top of her one-piece. In 1982 it was replaced it with concentric W's (explained in-story as the logo of the "Wonder Woman Foundation" and, Post Crisis, as Diana Trevor's WAFS insignia). The eagle has recently returned.
 * The various OMACs all have an eye symbol on their chests, representing their connection to orbiting satellite Brother Eye.

Comics -- Marvel

 * Captain America's white star, though the pattern on his shield and the A on his forehead are also pretty emblematic of him.
 * USAgent, who was Captain America for a while in the 80s, has red and white stripes with a black star in the upper-left.
 * The Fantastic Four's 4-in-circle.
 * Spider-Man's spider at the center of his costume's web-pattern. (He also sports a more abstracted spider on the back of it)
 * The Black Costume/Venom had/has a larger white spider design that takes up most of the chest and back.
 * Ben Reilly had his own Spider-Man costume design, which Spider-Girl (Pete & MJ's daughter from an Alternate Universe Twenty Minutes Into the Future) adopted for her own series.
 * Arachne, another spider-themed female hero, uses the Venom-style design.
 * In fact her costume, back when she was the current Spider Woman, was the inspiration for Peter's original black costume.
 * A particularly extreme form of insignia is the dragon symbol sported by Iron Fist -- actually an exotic burned-in scar received during his origin story. Previous Iron Fists have had it in other places. A villain who hates the Iron Fist legacy tried to burn the symbol off Danny's body.
 * Guardian, leader of the Canadian superteam Alpha Flight, has a large red maple leaf that wraps around the left side of his chest. At one point, the whole team got similar uniforms.
 * The Punisher sports a prominent skull on his chest -- like Batman's symbol, a heavily armored target.
 * In some issues, the teeth are spare ammo magazines.
 * The X-Men have an X in circle logo. It usually isn't in the middle of their chest, but it still counts.
 * Emma Frost has a particularly Stripperific variation on the X logo; it's made up of the exposed portions of her skin.
 * Most versions of Sunfire's costume have a red circle and lines across his chest that evoke the Japanese military flag.
 * Havok used to use a pattern of circles within each other that looked similar to the way his energy blasts are drawn. Nowadays he just has a glowing circle with lines reaching out of it.
 * Daredevil has two interlocked Ds. His original costume, however, had just the one.
 * Ms. Marvel has a large lightning bolt across her chest.
 * Shen Kuei, aka The Cat, has a large black cat tattooed onto his chest.
 * Deadpool's, erm, "Deadpool Symbol" (a simplified version of his mask), makes an appearance on his belt buckle, his weapons, his boxers and on the center of many of his shirts.
 * Generally averted by Rob Liefeld's creations, who are instead identifiable as superheroes by their Many Belts, improbable anatomies, Shoulders of Doom, and thousands upon thousands of pockets. Nevertheless, a few -- like Shatterstar -- do go in for a Chest Insignia.
 * Thor and Iron Man have costume details which serve this purpose. The former has the six circles on his chest plate, while the latter has the uni-beam, which is usually circular or pentagonal.
 * Norman Osborn's Iron Patriot armor also has a Uni-Beam, shaped like a star. This feature ironically causes the Uni-Beam to overheat after multiple uses, used to the advantage of Spider-Man in their most recent fight.
 * Jamie Madrox, aka Multiple Man, has "spots connected by lines" that were originally part of an impact-reducing full-body suit but have since retreated to the chest.
 * Daimon Hellstrom, the Son of Satan, has an inverted five-pointed star within a circle tattooed on his chest. He usually goes shirtless to keep it on display.
 * In his full garb as Sorcerer Supreme, Doctor Strange's typical tunic has a blue 'demon' with upstretched arms. His new wardrobe in the 2011 revival of The Defenders has a red trident-like symbol which resembles it.

Comics -- others

 * The Astounding Wolf Man has his wolf insignia on his bulletproof armor.
 * The French superhero Superdupont has an insignia with the letters "SD" inside a tricolore (blue-white-red) cockade.
 * Mike Baron & Steve Rude's space hero Nexus has a lightning bolt symbol, off to one side.
 * In Johnny Saturna saturn symbol is worn on the chest of both Johnny Saturn I (John Underhall) and Johnny Saturn II (Greg Buchanan). In the Spire City / Johnny Saturn universe, superhero heraldry has come to include letters, element symbols, and more subtle symbolism.
 * All Fall Down gives us Portia, Paradigm and Siphon.
 * Super Dinosaur has an "SD" on the front of his standard harness.

Films -- Animation

 * There's the "i" in an oval sported by The Incredibles. Even the villain Syndrome sported an "S" that covered his entire torso.
 * In Bolt, the white-furred dog who is plays a canine superhero has a black lighting bolt Phlebotium-imprinted painted on his side. A justified variant, as Bolt's breastbone usually faces the ground and an insignia there wouldn't often be seen.

Literature

 * The Redcross Knight in The Faerie Queene has a, you guessed it, blood red cross on the front of his armor.

Live Action TV

 * Many incarnations of the Super Sentai / Power Rangers feature Chest Insignia. Sometimes it's a team logo, sometimes it's a personal one. A few have the smaller offset-to-the-side version. Logo belt buckles are also used but they're generally not as visible.
 * Notably, the original Ranger team only had the belt buckle versions (except for the White Ranger), though the trope was apparently powerful enough that they got moved to the chest for the merchandising and in the movie.
 * Parodied in the live-action series of The Tick. Captain Liberty's chest insignia is a star cut out of her uniform, revealing some fine Fan Service underneath (compare Power Girl). The supervillain Destroyo even makes light of this the episode "The Tick v Justice" -- referring to her insignia as "your star full of cleavage."
 * Lazy Town's resident "slightly above average hero", the unfeasibly athletic, blue-bespandexed Sportacus, sports a chest badge that reads "10". The number indicates his heritage (he's tenth in a line of similar protectors) and carries connotations of his being a "team player".
 * El Chapulin Colorado had its red "CH" inside a yellow heart.
 * Not quite heroes, but there's the minor fact that Star Trek featured the small-bit-on-the-side version. To the point where some of the fluff says the Enterprise's then-unique pointy thing became Starfleet's actual official insignia so everyone could wear it.
 * The many versions of the Japanese Superhero Ultraman always have a light on his chest, which flashes to indicate how much energy he has remaining.
 * Kamen Rider OOO has one which changes depending on which Core Medals are currently in use.
 * The Ambiguously Gay Duo have G for Gary and A for Ace. Unsurprisingly, there happened to be times when they had to stand next to something large and Y-shaped.

Pro Wrestling

 * Professional Wrestlers who wear singlets often adopt a chest emblem. Wrestlers with other styles of ring gear often wear similar logos on their legs, crotch, or butt.
 * Bret Hart had the winged-skull-inside-a-heart
 * Kurt Angle sported an "A" inside a pentagonal shield for Kurt Angle--meant to evoke Superman's famous S-shield
 * The distinctive "nASh" across the chest of Kevin Nash.
 * In a direct reference to the Superman "S" shield, indy wrestler Chris Hero sports a Superman-style shield with the letters "CH" in it.
 * And then there was the Hurricane (Gregory Helms), whose gimmick was thinking he was a superhero. Naturally, he wore a 'hurricane' symbol with an H in the centre on his costume. His sidekick Rosie, once he 'graduated', sported an R. Since Rosie was about twice the size of Hurricane, his R was about twice as big as Hurricane's symbol.
 * Shark Boy, at least before becoming Stone Cold Shark Boy, had the clear shark motif on his outfit.
 * TNA wrestler Suicide has his full name in block lettering written over a vaguely M-shaped logo on his chest.

Video Games

 * City of Heroes allows players to choose chest insignia from over a hundred symbols, plus every letter in the Greek and Roman alphabets and all ten decimal digits.
 * Although the letter and number options are pretty rarely used, as they look kinda silly.
 * Most Navis in Megaman Battle Network have their characteristic insignia in a circle on their chest. MegaMan.EXE himself has a stylized H, which stands for "Hikari," the family name of of his operator Lan
 * Ditto Geo in Mega Man Star Force, though there's only one or two other characters that have one.
 * While it's not superhero exactly, who doesn't wear a tabard with a chest symbol in World of Warcraft these days? Not only can they cover some of the uglier chest armor, but they're good for showing whose guild you're in or what faction you're exalted with, or what achievements you've earned.
 * Jecht from Final Fantasy X and Dissidia Final Fantasy has the logo of his sports team tattooed over his always bare chest.
 * In Comic Jumper, Captain Smiley has one that obnoxiously snarks back at him called Star.
 * The faux-Contemptible Cover of MegaMan 10 gives Megaman one of these, an "M" in a six-sided figure. In the official art (and actual games), he has superhero Underwear of Power, but no insignia.
 * Although it's not exactly in the middle of his/her chest, Commander Shepard in Mass Effect has the N7 emblem (basically the Alliance's version of a Ranger Tab, although Shepard is the only character seen thus far to have it) on the left breast of their default armor. In the 2nd game it also appears on all non DLC, customizable chest plates. Promotional images for the third game reveal Ashley Williams to have her own version of the armor with S1 in place of the N7.

Web Animation

 * Though not quite a superhero, the star on Homestar Runner's shirt has become emblematic of the series. Strong Mad similarly has an M on his singlet, and Homsar has his entire name on his shirt. Coach Z also wears a "Z" emblem on his footy-pajamas/stomach.
 * The Coach fancies himself a rapper; that might actually be Flavor Flav-style bling.
 * In the third season of Red vs. Blue, the engine used to film the series was changed when Halo2 was released. In the game the player can customise their character with different insignias (although they wear them on their shoulders rather than the chest). The main cast feature their own personal symbols at first, but they were short lived.

Web Comics

 * In The Inexplicable Adventures of Bob, after Bob very briefly becomes a Superhero and then loses his powers, he says his one real regret is that he used a permanent laundry marker to make the "B" logo on his shirt.
 * Lampshaded in Everyday Heroes. Team leader Matt O'Morph has a super-flexible boneless body; in the same way, his chest emblem is an irregular blob that changes shape in every panel.
 * His teammates have more traditional symbols: Mr. Mighty's gold double-M in an oval, and Dot Dash's dot-and-dash (a convoluted pun on her real name).
 * Skull Girl from Super Temps has a pair of...erm Chest Insignias conveniently positioned.
 * Arachni-Guy from My Roommate Is An Elf has the number 8 with eight stick limbs protruding from it (two for his arms, two his legs, and four for his metal limbs that extend from his back.
 * Homestuck characters get super-hero style clothes with their Aspect's symbol featured prominently on the chest when they ascend to God-tier.

Web Original

 * The Global Guardians PBEM Universe: Given that the game is about superheroes, these are common.
 * Captain Hammer in Dr Horrible's Sing-Along Blog has a common-or-garden claw hammer on his T-shirt.

Western Animation

 * All of Ben's alien forms in Ben 10 have the Omnitrix symbol on them somewhere, usually the chest, but the shoulder, forehead, and wrist are also common options. Grey Matter is the form with the oddest placement. It's much larger than usual given Grey Matter's small size, but on his back, where it's not usually visible. Justified in that the symbol basically is the Imported Alien Phlebotinum that lets him turn into those alien forms.
 * It eventually gets his identity exposed in Ben 10 Ultimate Alien: A young fan noticed that there were a bunch of aliens wearing the same symbol in about the same area, and after poking around that area found that Ben wore an identical symbol on his watch...
 * The Plumbers in Alien Force and Ultimate Alien have badges (identical to Ben's Omnitrix symbol, which was likely based off the Plumbers') that they wear on the chests of their armor.
 * Although he didn't have it at the beginning, Danny eventually (although in an incredibly convoluted manner) gets his own at the beginning of the second season in Danny Phantom as a stylish "DP".
 * Dani, on the other hand, has her logo slightly off center.
 * Freakazoid has a "F!" on his chest.
 * Danger Mouse has "DM". It's off-centre in a similar manner to Robin's.
 * Also turned up in Thunder Cats: the Thundercats themselves had the roaring-jaguar insignia that the Eye of Thundera projects, and Mumm-Ra sported an insignia on his bare chest depicting intertwined serpents.
 * In ThunderCats (2011) The Blue Blood, Royal Blood and soldiers of Thundera all sport large red cabochons on their clothing, either chest or belt-mounted, and their shields, meant to evoke their Power Crystal, the Eye of Thundera. It's even present on a Thunderian Sphinx. The Cat-headed Iconic Logo carried over from the original is the royal emblem, seen in the castle throne room, and projected as a Bat Signal, but does not appear on armor or clothing, in part as a deliberate effort to avert instances of the Unreliable Illustrator.
 * Most Transformers sport the robot-face Autobot or Decepticon logo prominently on their chests (Others may have them on their shoulders, or wings if they have an aerial alt-mode). Skyfire switched out his own logo to indicate he'd defected, demonstrating that these logos are removable, not painted or embossed. (Magnetic patches, perhaps?)
 * Some of the Decepticon ones, at least, are brands: see Transformers Animated, when join the Decepticons.
 * In Visionaries each warrior has a totem on their chestplate that represents their animal form.
 * In the various My Little Pony series, each pony has a symbol on their flank (known as a "cutie mark" in My Little Pony Friendship Is Magic) corresponding to their name and personality.
 * Care Bears and their Cousins also have symbols unique to each character. As an added bonus, these symbols double as a weapon.
 * Liberally doused the Legion Of Super-Heroes cartoon. Every characher wore a ring and belt with the legion insignia and each characher had a symbol that reflected their powers. If they didn't have the symbol on their chests, it still showed up in the show intro and several times during the show, usually on computer screens.
 * Subverted in the Tick with Four-Legged Man, whose chest reads "(4 legs)". Parentheses included. The Tick's own chest is pure blue, whereas Barry, the jerkass self-styled superhero that was trying to steal the Tick's name, had a big tick outline on his chest.
 * The mooks working for MAD in Inspector Gadget often went out in public in outfits with the MAD emblem on it. Despite this, the title character never once realized that said individuals worked for MAD.
 * In Re Boot Bob's gold and black icon was displayed over his heart like a sheriff's badge. After he merged with Glitch his icon moved to the center of his chest and had a gear shaped symbol added around it.

Real Life

 * Oddly, this trope is Older Than Print: Knights on the Crusades typically wore white surcoats with red crosses on their chests. The Knights Hospitallier (a.k.a. Knights of Malta) kept their trademark red surcoat with white cross long afterward.