Aang: Sorry about your boomerang, Sokka. Sokka: I feel like I've lost part of my identity. Imagine if you lost your arrow, or if Katara lost her.... hair... loopies. Merchant: Here's your produce, ponytail guy. Sokka: (dejectedly) I used to be boomerang guy...
An Iconic Item is an object carried or used only by one specific character, which also serves to define the character. Seeing it immediately brings that character to mind. Seeing the object abandoned (i.e., on a battlefield or in a ditch) would cause the character's friends to worry about his safety. Usually concludes with the character in question casually walking up shaken and asking if anyone has seen his Iconic Item.
Such safety worries would be on a sliding scale of realism; Cap's shield is one-of-a-kind, but there may be manySpidey outfits or beat-up brown fedoras out there. Provenance would have to be established before a search party is called.
If the Iconic Item just so happens to correlate with the character's personality or traits, which it's going to 90% of the time, it's probably also a Weapon of Choice.
Often produced as Official Cosplay Gear. Compare Clothes Make the Legend and Iconic Outfit. Also compare National Weapon for a type of cultural Iconic Item.
JoJo's Bizarre Adventure: Will A. Zeppeli's top hat, Jotaro's student cap, Josuke's pompadour (technically not an item but he still considers it to be a strong part of his identity, and a Berserk Button if mocked), Gyro's steel balls, Johnny's horseshoe jockey cap. The list could go on forever, but these are just a few of the big ones.
Haruhi Suzumiya's yellow hair ribbons, Yuki Nagato's glasses, and Mikuru Asahina's cosplay costumes, especially her maid costume.
Many of the Angels in Kidou Tenshi Angelic Layer would count; more than tools to their users, who even talk to the robotic dolls on more than one occasion, an abandoned Angel is a sign that something is deeply wrong with its operator.
Most of the main characters' cards in Yu-Gi-Oh! and Yu-Gi-Oh! GX. Somewhat believable in the case of Kaiba's Blue-Eyes White Dragons, since there were only four in the world, and he has three (he ripped up the fourth as soon he got his hands on it to prevent anyone else from using it, because only three copies of any given card may be used in the same deck). Yugi's Dark Magician is a bit of a stretch, but has been established as a rare card, maybe not the same rarity league as a Blue-Eyes, but enough so that only one other duelist is ever shown using one. However, Mai's Harpie Ladies or Asuka's Etoile Cyber are common cards that could have been dropped by anyone, which raises a few questions as to iconic status.
Ditto for certain cards in Duel Masters, most recognizably Shobu's Bolshack Dragon.
Guts from Berserk actually has three of these, his BFS The Dragonslayer, his mechanical hand and his Berserker armour, all of which are one-of-a-kind items that match his personality.
While all the pilots in Neon Genesis Evangelion wear a headset to help them link with their Eva units, Asuka wears hers with her civilian clothes as well (wearing them like barrettes). This helps to establish certain things about Asuka. On a personal level, she is proud to be a pilot, and doesn't want anyone to forget it. The shape of this gear also gives her "horns" like a female Oni (ogre) like another character we could mention. It's worth noting that oni musume (ogre's daughter) is roughly the Japanese equivalent of "bitch".
Black Cat: Train's orichalcum custom-made gun with the distinct number XIII etched on the sides.
Vash The Stampede's very distinctive revolver, and Wolfwood's massive cross (both from Trigun). Also Vash's distinctive sunglasses with the W-shaped earpieces, which he puts on whenever it's time to get dangerous.
Ahiru's pendant in Princess Tutu. If you see it laying around, she IS in trouble—she can't be a girl without it.
Played with in an episode of Digimon Adventure. Mimi runs ahead, and gets carried off. When Taichi and Koushirou find her pink cowboy hat lying on the floor, they barge in to rescue her, only to find her enjoying a bath. Needless to say, Mimi starts throwing things.
Taichi's goggles themselves are an example of this trope, as is Yamato's harmonica (which becomes a minor plot point late in the series), Koushirou's computer and Sora's hat/helmet thing.
Many Digimon have iconic items — Tailmon's tail ring, Wizardmon's staff, etc. There's probably many to count.
Across the entire franchise, everyone's specifically coloured variant of the Digivice is also this, being possibly the most personally-associated belonging any character has. Adventure also gives this treatment to their Crests, Digimon Adventure 02 doing the same for their Digimentals.
Kenshiro's jacket in Fist of the North Star. It's so iconic that it inexplicably reappears on him after every fight where he rips it beforehand. When he tears his shirt, it's usually a surefire sign that someone is going to die.
Ryouga's trademark bandanna from Ranma ˝, and he went as far as wearing dozens of them, one over the other, to use as weapons in his first match with Ranma.
Mousse's glasses, Ukyou's giant battle spatula, Nodoka's family sword, Cologne's staff, Kodachi's ribbon, and Ryouga's umbrella also qualify as personality-defining items. On the "worrying about their safety" angle, Ranma once found Akane's schoolbag, recognizable by the doll hanging off it, and deduced she was kidnapped (although that was the item's only purpose in that story and was never seen before or after.)
Kamina's glasses and Simon's drill pendant from Tengen Toppa Gurren Lagann. Kamina even gives Gurren the glasses by melting down the swords it originally had.
Kamina's glasses are so associated with him that the particular style of angular sunglasses he wears are now near-universally called "Kamina shades", even by non-Gurren Lagann fans.
Asuma's cigs and trench knives in Naruto. So much so that Shikamaru's salvages them and gives them a significant part in his plan to take revenge after Asuma's death.
Mahou Sensei Negima! carries a small few of these, most notably Asuna's bells given to her by Takahata.
Luffy's straw hat in One Piece. Zoro's haramaki, and Chopper's hat (Before the Time Skip) also counts too.
America's bomber jacket, to the point that fans depict it as a sort of security blanket for him. If he dates someone, expect them to wear the jacket at one point or the other.
The Italy curls as well. Most fanworks (Written or drawn) identify it's content by describing the curls. Ex) The young boy laughed; his auburn hair shaking into his face, except for one obstinate curl on the side of his head.
Haruko's engine-powered Rickenbacker bass guitar/multi-purpose weapon from FLCL.
Natsu's scarf in Fairy Tail which he's always seen in. Even while sleeping. When Lucy accidentally yanked it off him (trying to pull it up) and he didn't seem to notice, she knew something was wrong.
His scarf is a gift from his dragon-foster-father Igneel. It's probable made of dragon skin. It's a Chekhov's Gun, as it later protects Natsu from Zeref's death magic.
Ash Ketchum's hat, to the point where he will yell at and pursue any Pokémon that steals it (except on one occasion).
In Pokémon Special, most of the Dex Holders wear an extra accessory (or have a slightly different physical feature) to differentiate them from the characters they were based on. Gold has his goggles and cue, Crystal her star-shaped earrings, Silver his black gloves, etc.
Certain Pokémon also count in Fanon: May is synonymous with a Torchic starter, Brendan with Mudkip, Dawn with Piplup, Red with Pikachu, Blue with Eevee, and Bianca with Munna, just to name a few.
Ash's Squirtle from the Squirtle Squad has pretty awesome sunglasses reminiscent of Kamina's. Yeaaah...
His Treecko has the twig he likes to put in his mouth.
His Krookodile has his pair of sunglasses, like Squirtle.
Makoto Kino from Sailor Moon never takes off her pink rose-shaped earrings, even after transforming into Sailor Jupiter. Sometimes she uses them as projectile weapons, and more than once the sight of them has snapped Usagi back into remembering.
Captain America's shield. As the theme song reminds us, all those who chose to oppose the shield must yield. Indeed, when Cap was "dead" the question of who would carry the shield was a major plot point.
Even though there are 7200Green Lantern rings they are keyed to specific people who all live in different parts of the galaxy and if one is lying around the owner is usually in grave danger.
Less well known but many versions of Wally and Barry always have the ring that contains their suits somewhere on their person.
Of all the Bat-gadgets, the Batarang is probably the only one notable enough to count, along with the concept of the "utility belt" in general.
Spider Jerusalem's oddly impractical sunglasses from Transmetropolitan. They're shaped like that because they're a combination of shades and a digital camera, specially designed for his journalist work. Also because the machine that made them was on drugs. No, seriously.
Wesley Dodds, the Sandman, has his gas-mask, a perfect complement for his sleeping gas gun. Neil Gaiman gives Morpheus, king of dreams, a similar looking helm, but he wears it far less often.
Doctor Strange's red Cloak of Levitation and the Eye of Agamotto, which were later retconned to be icons of the office of Sorcerer Supreme and not of Strange himself.
Many of Batman's Rogues Gallery. Two-Face has his two-headed coin; the Penguin has his top hat, monocle and cigarette holder (and his gimmick umbrellas); the Mad Hatter his top hat; Ra's Al-Ghul his high collared cape; etc.
Speaking of Arm Cannon weaponry, there's also Ashley J. Williams from Evil Dead. Only instead of an arm-gun, he lopped off his hand and lashed a chainsaw onto it. This and his sawed off, back-holstered, shotgun are easily the most iconic items for Ash.
Princess Leia 's hairstyle and long white dress in A New Hope.
Darth Vader's entire costume
Mace Windu's purple lightsaber and Darth Maul's double-bladed lightsaber are unique weapons (all lightsabers are different, but Windu and Maul's are the only ones of their kind seen). Notably, the purple lightsaber was Samuel L. Jackson's only demand for accepting the role. Though this doesn't carry over into the Expanded Universe, where purple is a 'neutral' color used by Jedi and Sith, and double lightsabers are present but not common. Lightsabers in general are iconic weapons for the franchise.
Anton Chigurh's coin, captive bolt pistol and sound-suppressed Remington 11-87 semiautomatic shotgun in No Country for Old Men
In Aladdin, Genie's shackles. When he's freed and they disappear it looks kind of weird. The makers of the TV series apparently agreed and he got them back.
In the 1976 film version of Carrie, Norma is never seen without her red baseball cap. She wears it in gym class, during detention, and even at the prom. The only two times when she's not wearing it are when she's getting her hair styled (and even then, it's perched atop the giant hair dryer), and when Carrie knocks her flat on her ass with the firehose and kills her, blowing her cap off in the process. The cap was reportedly the idea of her actress, P. J. Soles.
In Hoodwinked!, Red Puckett brilliantly lampshades it:
Red Puckett: They call me "Red" because of this red hood I wear.
Nicky Flippers: What about when you're not wearing it?
Red Puckett:[quietly] I usually wear it.
Jacques Tati as Mr. Hulot: small hat, beige rain coat, long pants, pipe.
Mad-Eye Moody's mad eye. After he dies in Deathly Hallows, Harry sees it stuck on Umbridge's office door in the Ministry of Magic and is so infuriated that he steals it back, tipping her off that there are intruders in the building.
The Dresden Files: Harry Dresden's black leather duster. If that isn't present, his battered silver pentacle is.
Rincewind's hat in Discworld. Of course, all wizards and witches wear a pointy hat, but Rincewind is the only one who finds it necessary to write "WIZZARD" upon it in sequins. And he always comes back for his hat. (Although at the start of Interesting Times, he's been separated from it for some time while on a Deserted Island, and found it necessary to construct a replacement ("a Cargo Cult wizard's hat") out of grass and bamboo. With "WIZZARD" spelt out in cowrie shells).
Don Quijote, his suit of armour and the "golden helmet of Mambrin" (actually a barber's brass shaving-bowl).
Les Misérables: Jean Valjean is rarely ever seen with them — in fact we only learn he has not sold them at the end of the book — but the silver candlesticks he received from Bishop Myriel are quite iconic to him. Film adaptions enlarged this.
The Seventh Doctor carried around a crazy umbrella with a question mark for a handle.
The Eighth Doctor's Wild Bill Hickok costume.
The War Doctor's costume was a mix of 8's Victorian waistcoat and the Ninth Doctor's leather jacket, with a Badass Bandolier that also serves as a Tragic Keepsake.
The Ninth Doctor's leather jacket.
The Tenth Doctor also had a pair of "brainy specs" like Fifth, and he also wore a brown overcoat near constantly. Along with his trainers, another feature from 5.
The Eleventh Doctor is the Trope Namer for Bowties Are Cool. In fact, each Doctor has some form of iconic item. The First has a cane or ring, the Second has his recorder, the Third has his frilly shirts and capes...
Some of the Doctor's companions also had an iconic item associated with them. Examples include Jamie McCrimmon's kilt, Adric's badge for mathematical excellence (the shattered remnants of which featured in an Empathy Doll Shot after the character died) and Ace's badge-covered black jacket.
In Real Life, the show in general has the iconic police box outer form used by the TARDIS. Even before advances in communications technology saw the police box retired from its original function, it was heavily associated with the show to the point where the BBC won the rights for it off the police.
In Star Trek: Deep Space Nine, Captain Sisko acquired a baseball in an early season, which he kept on his desk. It acquired great significance in the later seasons: When the station has to be abandoned to the enemy, Sisko leaves the baseball behind, to tell his nemesis that he expects to return for it. Later, when Sisko has a breakdown and goes to Earth for some soul-searching, he brings the baseball with him, indicating that he is not sure if he will ever come back.
Much's hat. He's only seen without it about three times. Subtly lampshaded in the show itself as when Robin is minutes away from death he makes a point of grabbing it off Much's head before he says goodbye.
To a lesser extent: Will's axe, Little John's staff and Robin's recurved bow are all practically synonymous with their characters. Kate is renowned for her forehead braid, though this is more the result of Memetic Mutation considering she only wore it for three episodes in total.
House's cane counts, though he goes through a few in differing styles (the one with the flames is the most distinctive). His vicodin bottle could count as well.
Booth's "Cocky" belt buckle in Bones. Brennan actually worries about him when he takes to wearing normal belts after his brain tumor.
Sid from CSI: NY has the iconic glasses that come apart in the front. (These are called Clic Readers, and can be purchased online, along with several other styles; the store even uses a picture of Sid on their website.)
And Mac from NY has the lapel pin he always wears.
In Law & Order: Criminal Intent, Goren uses his pocket knife a lot (not as a weapon mind you, just to pick up stuff he doesn't want to touch, dig stuff out of walls, etc).
Hannah Montana's blonde wig. And her pink, sparkly jacket. And in the last two seasons, the single glove.
In Ugly Betty, Betty's Red glasses and pink brasses. Although she finally gets the braces removed in the final fourth season.
"Boston" Rob Mariano, from Survivor and The Amazing Race, has his Boston Red Sox hat. At one point on The Amazing Race 7, he gives a local the blue Red Sox hat he traditionally wore on Survivor, and from the next leg on (including on All-Stars) he wore a red one instead.
Sherlock: Sherlock's Badass Longcoat, his Scarf Of Ass Kicking, John's cuddly jumpers, and Mycroft's umbrella. Sherlock is also commonly depicted in fanworks as wearing the "Purple Shirt of Sex" as dubbed by the fandom.
The Closer: Brenda's purse, a huge black thing that she would be completely lost without. Lampshaded in the finale, when Brenda is forced to shoot Philip Stroh through the bottom of it, and the rest of the Major Crimes unit all get together and buy her a new one exactly like the old one because she doesn't look right without it.
Sparadrap's staff in Noob is recognizable enough among the fandom to have its own T-shirt. The MMORPG setting and the fact that players that have reached the level cap are on Equipment-Based Progression keeps most items owend by the other characters from sticking around long enough to get any kind of permanent association with them.
Buckethead's white mask (recently used by the Jabbawockeez too, though) combined with the plastic bucket he wears on his head.
Claudio Sanchez's legendary hair. If not that, then his collection of personalized Gibson Explorers.
On the subject of hair, Ray Toro's fro pretty much has its own fanbase.
Ian Dury's caliper and walking stick. The latter is an interpretation of Hit Me With Your Rhythm Stick
John Otway's Rumplestiltskin Baby. A roadie throws it up on stage whence John drops it. Later smashes it against the mic during Headbutts.
Lights early on in her career would wear a brightly-colored headband; however, she no longer wears the headband nowadays, ultimately subverting this trope.
Kaizers Orchestra had the World War I gas mask worn by the organist. All of the three first albums feature the mask prominently on the cover art and the band's live performances involved the mask staying on for the entire set, rendering the organist into The Faceless and The Voiceless (since it's impossible to speak through it).
Maurice Chevalier and his yellow straw hat.
Louis Armstrong always has his trumpet nearby, of course, but his handkerchief is equally iconic.
Luciano Pavarotti also always carried a handkerchief when performing.
The Sword Excalibur. In addition, the Sword in the Stone (Caliburn), to the point that both swords are often mistaken to be one and the same. Although in some cases they are; Arthurian canon is sketchy and full of retcons and Alternate Continuity. The problem is of course that in most pictorial representations it is impossible to tell Excalibur apart from any other old sword and thus you need other factors to e. g. tell whether a statue is meant to represent Arthur or some other king.
Mythologies in general identify deities with their iconic weapon, tool, or article of clothing.
Such items can be essential to tell whom a sculpture is meant to represent.
The Venus de Milo lacks arms and thus holds no objects in her hands, so people are still debating whether she is in fact a representation of Venus/Aphrodite or some other Goddess.
These identifiers can sometimes take on a life of their own:
The resurrected Christ can also be shown holding a spade, as the New Testament mentions that the first witnesses mistook him for a gardener.
Since artists and sculptors generally did not know what Christian saints and martyrs looked like, the way to tell which saint a painting, stained-glass window or sculpture is meant to represent most frequently an iconic item such as the instrument of torture or implement of execution used on them or an object connected with an important episode in their life etc. These objects often can be used as symbols of the saint without actually showing the saints themselves, e. g. when a city's coat of arms features one or more keys, it usually means that it has a cathedral or major church dedicated to Saint Peter (who holds the keys of heaven) or is somehow connected to the his successors, the papacy (such as the arms of Avignon in France). Other examples:
St. Andrew: An X-shaped cross, better known as a St. Andrew's cross (or saltire).
St. Antony the Eremite: A staff ending in a T-shaped cross. Also a pig.
St. Catherine: A broken wheel and a sword.
St. James: A pilgrim's hat and scallop (seashell).
St. Laurence: A griddle (on which he was roasted alive).
St. Nicholas: A bishop's mitre and three golden balls.
St. Mary Magdelene: A vessel of ointment.
St. Stephen: Three stones on a book.
Paintings and sculptures of Hindu deities hold all kinds of iconic objects in their hands (it helps that they often are represented with more than two arms). Among the most widely known ones are Shiva's trident and Kali's necklace of skulls. They also generally ride on or are accompanied by an iconic animal, e. g. Ganesha always has his rat with him.
Certain Buddhist deities are known for items they carry. In case of Bishamontennote known Vaisravana outside Japan, he carries a small pagoda and a spear. The items have their meaning: in case of Bishamonten, the pagoda symbolize the teaching and the spear symbolize the willingness to defend the teaching.
Signature Gear in GURPS cannot be permanently stolen from the player and is only truly lost if willingly sold or physically destroyed (and in that case you get a new one).
In Warhammer fantasy battles many special characters have this, be it a flying longship (Wulfrik), an indestructible throne (Thorgrim) or a legendary hammer owned by the first emperor (Ghal Mharaz owned by Karl Franz).....There are many more examples but this will do for now.
Warhammer 40,000 Imperial Guard heroes could take a Trademark Item as an upgrade in the previous codex. It made his unit less likely to retreat, but they might panic and run if he died.
Several of the Noble Knights in Yu-Gi-Oh! have a Noble Arms clearly associated with them: Artorigus has Caliburn. Laundsallyn has Arfeudutyr. Gawayn has Gallatin. Gwalchavad has Destiny, but surprisingly not Excaliburn, however, as it appears to be used by both Artorigus and Laundsallyn in their respective upgraded forms.
Pathfinder gives Clerics weapon proficiency with their deity's iconic weapon. So the cleric of the badass God of Archery can be appropriately armed with a proper bow.
The silver candlesticks given to Jean Valjean by the Bishop of Digne. Not seen that often, but when the lights fade to black at the end of the last note of the show, the candles are still burning bright.note And swiftly extinguished by the stagehands.
Also, Enjolras's red and gold vest.
Wicked: Elphaba's witch hat is this both in and out of universe. Also, Glinda is often pictured in fanart in her pink dress and the Flower in Her Hair from "Popular".
In Final Fantasy VI, Locke's headband. Finding it tied around a pigeon's wing gives Celes hope that he's still alive.
Tidus' J-shaped pendant in Final Fantasy X. Particularly significant since it's actually the personal insignia of his father, Jecht, whom Tidus has a beef with. In X-2, Yuna takes this emblem for her very own, to represent her memories of Tidus.
Ness' baseball cap in EarthBound. In the Japanese version, when Ness explores Magicant (the realm of his mind), his sprite shows him wearing his baseball cap and nothing else. All 3 protagonists in the MOTHER franchise wear a striped shirt.
Mario's hat. In Super Mario 64, if his hat is lost or stolen, he'll take double damage until he gets it back.
In Super Mario Sunshine, if it's lost or stolen, he'll actually take damage every few moments because he's not wearing it. Justified because the strategy guide says he's getting sunburn without his hat protecting him.
Luigi has never had an appearance in a game without his hat. In Super Mario Galaxy and the sequel, he keeps it on all the time, while Mario sometimes takes his off for a few seconds.
Sonic's red sneakers. Certainsources say that these are actually specifically designed for him, to avoid burning his feet while running.
Sonic's nemesis Dr. Ivo "Eggman" Robotnik also has his Eggmobile, a rotund hovercraft that is used as his personal transport and as the cockpit of his manned machines. His Scary Shiny Glasses would count as well.
Amy Rose is rarely seen without her hammer, except in Sonic the Comic (where she uses a crossbow).
Zero's helmet is used for a particularly symbolic, yet sad, example in Zero 4. It's lying on the ground broken, and Zero is dead, and he doesn't have to fight anymore; because, whether or not Zero survived (still heavily disputed by the fanbase), the war is over.
Mega Man & Bass has the helmet of the character you are playing as lying on the ground if you got a game over.
Proto Man's shield is iconic enough that Mega Man was shocked when Proto Man gave him his shield in 7. It's an equippable item in that same game. In fact, his kart and transportation items are all modeled after his shield.
Similar to the Eggmobile example above would be the Wily Capsule, often described as "the form that will haunt Mega Man for ages."
In the manga Ryu Final: Street Fighter III, Ryu has tied his headband to a post in the ruins of Suzaku Temple, where he trained with his master and eventually faced Akuma in one Final Battle. Aspiring warriors travel to this location to find the headband, where Ryu awaits. It is a symbol of how he has finally achieved peace as a warrior, and now dedicates himself to raising the younger generation.
Sakura's white headband mimics her hero Ryu's headband from his early days as a street fighter, before Ken replaced it with the red one.
There are several others. Rose'sscarf, Guile and Charlie's dogtags (Guile later taking the presumably KIA Charlie's dogtags for his own), Dhalsim's necklace made out of the skulls of the children in his village who died from famine, Fei Long's nunchaku, Dee Jay's maracas, etc. Of special note is Guy'ssneakers, popular enough to spawn a meme ("Realninjas wear Nikes!").
Half-Life - Gordon Freeman's crowbar. To date he's had five (and subsequently lost four) of them. Also the Gravity Gun in Half-Life 2 and its episodes. Also, the HEV suit.
Garrus Vakarian's visor in Mass Effect, and Commander Shepard's N7 armor.
Snake's (Solid and Naked, not Liquid or Solidus) Cardboard Box.
And, on the more normal side, there's his bandanna.
And his cigs. For a game that loves to make you procure on-site equipment, they go through insane trouble explaining how cigarettes are somehow smuggled along with him... including one example of Snake ingesting his cigarettes and then vomiting them up upon arrival.
Even more prominently Revolver Ocelot and his revolvers.
Nick Mason's Riot shield in Urban Chaos Riot Response. It's so iconic, people remember that part of his arsenal more than the pistol, which was featured in an in-game news cast. To the point where the Burners copy him and get their own. And taunt you about the fact they have their own.
Samus Aran's Charge Beam and Varia Suit, commonly found in every game, and the focus of most of the box art.
Her Arm Cannon — though in this case, it's literally her arm. Or, rather her Power Suit's arm.
And the friggin' Morph Ball.
And the Screw Attack — which, with a few key modifications, became the series logo.
The Ice Beam as well, both because of the unique platforming it produces from frozen enemies, and because of its significance as the primary weakness of the Metroids.
Her Missiles as well, with their distinctive rocket shape and red tip. So iconic, even more so than the unique round green-tipped Super Missiles, that in Metroid Fusion they made it so that it's the Super missiles that have the rocket shape with red tip and the normal missiles are just grey cylinders.
Most Harvest Moon protagonists wear a red neckerchief. Even some animals in the Wonderful Life subseries wear them.
Jazz Jackrabbit wears a red headband and totes a uniquely-shaped firearm. The artist’s proposed logo for the (canned) third game would included these elements, and there’s just something about the way they’re laid out...
Every protagonist has a Nice Hat which they can quickly be identified with. Even in Pokémon X and Y, which offers player character customization, you are still forced to wear a hat, although you do get to choose what hat.
Some Pokémon species have some: Cubone/Marowak has a bone club and a skull helmet, both from their dead mother. Farfetch'd gets a stick of celery it uses, pathetically, as a sword. Oshawott and Dewott have Scalchops, Scallops it uses as swords. Even when as Samurott it becomes a Dual BFS Wielding Pokémon, the battle animation for Razor Shell is still a Scalchop.
The Poké Ball, synonymous with the entire franchise itself.
Duke Nukem's golden Desert Eagle. Funny enough, a lot of people might not even realize he has an iconic item. It was absent in his best known game Duke Nukem 3D, and none of the games that came after it sold near as well. Strangely, it was changed to an M1911 in Duke Nukem Forever. His sunglasses, too.
Ragna's jacket, sword, and his copy of the Azure Grimoire.
Litchi Faye Ling's staff and panda hairclip, Lao Jiu.
Bang Shishigami's Nox Nyctores, Phoenix: Rettenjo (in the form of a giant nail), and scarf.
The blades of Nu-13 and Lambda-11.
Tsubaki Yayoi's Armagus, the Sealed Weapon Izayoi, and especially her Nice Hat with the eye (which is part of the aforementioned Izayoi).
Hazama/Terumi's suit and hat.
Like KOS-MOS above, Frank West can use a lot of different weapons, but is always seen (in promo material and official art) with Baseball bats. Taken Up to Eleven in Tatsunoko vs. Capcom, where Frank uses one in a hyper, and again in Case West, where he has an infinite supply of baseball bats unless the player gives him another weapon. Frank's Camera is also a pretty iconic item in the series.
The fourth installment gives us Leon's aviator jacket, which was actually sold as merchandise, at least in Japan. What makes it better is that Leon loses it a little ways into the game and 90% of the game is without it, and people STILL associate it with him.
From Fallout we have the iconic Vault Suit; each protagonist has had one with a unique number and is apparently the only canonical item of clothing he wears throughout his adventure if the endings are to be believed.
Benny's chequered suit and his stylized Browning HP Maria is also a highly prominent example considering he uses this combination to set the entire New Vegas plot line in motion.
While Madotsuki can equip various other objects, the one she's most often associated with is her knife.
In Rune Factory 4, Leon is never seen without his feathered fan, and Arthur is never seen without his star-shaped book. Strangely, he's not particularly a bibliophile (though he's got plenty of other nerdy qualities), but the resident Cute Bookwormisn't seen carrying around any of the many books he says he likes to read.
You don't get more iconic than Professor Layton's top hat. It pops up quite often in the puzzles and is the game logo. Story wise, no matter what you do, you will never convince the Professor to take it off.
Aubrey's choker (wherein it became a plot point when her soon-to-be-husband Jason destroyed it.)
Girl Genius: Agatha's trilobite necklace. The trilobite is the emblem of the Heterodyne family, but Agatha's is also a Restraining Bolt.
Torg in Sluggy Freelance had a flannel shirt, which has since phased out somewhat. Riff always has his sunglasses, and though he's depicted often without his trench, he will always be associated with some form of long coat, either duster or labcoat. Bun-bun will always have his switchblade and associated ka-click!
Tina of Wapsi Square is never seen without her choker, to the point where other characters speculate that it is there to keep her head attached.
Homestuck: Weapons of choice aside, John is strongly associated with the Con Air bunny he received as a birthday present three times over all on the same day. Jade was also associated with her pair of Squiddles dolls until having a nightmare about the things following the death of her dreamself.
The Order of the Stick: The main protagonist, Roy Greenhilt, is named after the green-hilted sword passed down through his family from his grandfather. It's the reason he became a fighter to begin with, and it's the symbol that allows his father's ghost to manifest on the material plane and talk to him.
In most series, the Autobot Matrix of Leadership is strongly associated with Optimus Prime, who carries it inside him. When it's seen in other hands, it's generally a sign that Optimus is badly injured, if not dead.
While not really an item, Optimus Prime's original vehicle mode. If he isn't a flatnose Mac truck, the franchise is RUINED FOREVER.
Pretty much every Transformer has some kind of weapon, gadget, special power, or altmode that's strongly associated with them.
In the episode "Boom Boom, Out Goes the Ed", Ed assumes the worst when all he can find of Edd is his trademark stocking cap, which he wears about 99% of the time he's on screen throughout the entire series. ("Double-Dee is double-done for!")
Also in the episode "The Luck of the Ed", Eddy is trying to reclaim his (brother') magazines, due to Ed misplacing them. Annoyed at his friends, and suspecting them, he steals Double D's hat and Ed's eyebrow, both of which they prized dearly.
Ed: But Eddy! I can't make funny faces without that!
Edd: (pulling Ed's pants close to his head) Wait, please Ed! I'm not decent!
Parodied in a SpongeBob SquarePants episode when Spongebob loses all his clothes in his efforts to escape Sandy's dangerous "pre-hibernation week" activities, and Sandy stumbles across them while looking for him.
Sandy: Spongebob's tie! And all his other little dressings! But he always folds up his clothes before runnin' around... in the nude! Something terrible must have happened to him!
Willy Fog himself has a top hat and a walking cane, the latter often being used in self-defense
Rigodon has a valise, as well as a bowler hat which he believes brings him good luck and refuses to replace when he briefly loses it
Tico is given an Ancient Egyptian "sun clock" early in the series and finds an excuse to consult it in nearly every subsequent episode
Princess Romy has a jeweled head-dress, revealed in one episode to contain medicinal chicken bones
Inspector Dix has a flat cap and a pipe, though he is never actually seen smoking
Avatar: The Last Airbender provides the page quote, from the episode "Avatar Day", where Sokka's boomerang gets stolen. He gets it back at the end of the episode, though. Some other examples are Aang's arrow tattoos or his glider, as well as Katara's hair loopies or water jug. Iroh and tea could also be thought of this way.
Every character on Scooby-Doo can be identified by their one outfit, but the most iconic item is Fred's ascot.
The Boondocks made a comment about how it is near-impossible to think of Martin Luther King Jr. in anything besides a gray suit... You just can't imagine him in a sweater and jeans sitting on the couch watching football or something. MLK destroys your image of him forever here
Any soldier's dogtags, to the point where if he's KIA, his fellows will try to at least get them back home. Which is why they're carried in the first place, of course. Although in another way they can and are seen as items that grind down soldiers' individuality and indeed humanity. Which is why they got the derogatory nickname in the first place ("we are treated like dogs").
Tom Landry's hat. If that doesn't motivate you, then nothing will.
General Douglas MacArthur is similarly known for his aviator shades, visored cap, and corn cob pipe. In fact, in a form of Memetic Mutation, he is actually the originator of the stereotype of military pilots wearing aviator shades; many of the officers that would go on to lead the Air Force worked for MacArthur earlier in their careers, in fact, also consider that he served as an officer in the Army from the turn of the century until the Korean War, and you begin to see just how many junior officers may have been inspired to imitate his style.
Gaius Julius Caesar wrote in his Commentaries that his soldiers would immediately recognize him by the red cloak he habitually wore. Many more modern renditions have him wear a laurel wreath at all times as well, as both Caesar and laurel wreaths are strongly associated with Rome.
Napoleon Bonaparte's distinctive bicorne (of a model quite different from those worn by others) and redingote grise (grey overcoat).
Horatio Nelson's eyepatch and empty sleeve. Possibly a subversion as, contrary to popular history, Nelson didn't wear an eyepatch. He was blinded in one eye, but the damage was all internal; the affected eye looked normal enough to be on display.
Current (as of 2013) Belgian Prime Minister Elio Di Rupo is so closely associated with his bowtie that the coalition agreement that formed his government is commonly called "the Butterfly Agreement" (as the words for "bow tie" and "butterfly" are the same in both French and Dutch).