Essentially the idea that when you're a slave, you need something to show it.
This trope centers on the times when a character who either is or was a slave bears some mark that sets them apart from other people. Most frequently this is either a burnt on brand, a tattoo, or even a serial number. Current slaves can also be marked by something as simple as a collar.
Often, a slave who has been freed will have this mark removed or, if that is not possible, altered. Another option is for them to display this mark openly, as if daring someone to comment.
Compare Mark of Shame, which this brand is to many slaves. See also Slave Collar, which is another way of marking a character enslaved, and Slave Race, where just being born a certain race is enough to mark you as property.
Slaves in Basara are branded to mark them as slaves forever. Shuri the Red King was branded when he was born by his own father after he heard a prophecy foretelling that Shuri would bring misfortune to him. Shuri understandably hates his father and prophets.
Black Butler's Ciel Phantomhive was branded on his back (Or stomach, if you're more the anime type) when he was kidnapped and kept as a slave. He is deeply ashamed of the mark and goes to great lengths to hide it.
In Naruto, the Hyuuga clan brands all of their branch house members with a tattoo upon their forehead which destroys their unique genetic abilities upon death, preventing outsiders from stealing them. While this might sound like a reasonable precaution in a world where bloodline theft is a common tactic between warring villages, the tattoos can also be activated at will by main house members with a secret handsign to cause intense pain or death, making the branch house members slaves in all but name to the main house. All known branch house members are so shamed by their "Caged Bird Seals" that they keep the tattoos covered up.
In One Piece, slaves of the World Nobility are marked on their backs with the "Hoof of the Soaring Dragon." This brand is meant to impress upon them the fact that they are less than human.
A group of slaves who were freed and became pirates altered this mark into one resembling a sun, which everyone on the crew, slave or not, adopted to remove the distinction of freeman and ex-slave.
Another set, one of whom is pictured on the image links page, took great pains to hide the mark, claiming it to be the result of a curse that caused anyone to see their backs to petrify.
Nami's Arlong tattoo could also be viewed as this. Nami herself certainly saw it that way. After she had stabbed out the tattoo, she had a new one put in its place resembling a pinwheel with a tangerine growing from it, to honor her adopted parents.
Shitsurakuen - Almost all girls (excluding Sora) have a symbol right above their chest symbolizing their slavery, and all males (and Sora) have a glove symbolizing rulership.
Berserk: As the only survivors of the Eclipse, Guts and Casca have the brand of sacrifice on their bodies (neck and breast respectively), which serves both to warn them that Apostles are incoming, but also draws Apostles towards them.
Gamzee in Hivefled is Covered with Scars, including a Glasgow Grin, and has the words "slut", "pet", "rape toy", "pail", and "worthless" carved on various parts of his body, along with his captor's sigils on his neck (Alternia's traditional method of marking slaves, rendered obsolete with the conquering of other species to use instead) and the magical binding "namoha" on his arm, which will imprison his spirit if he dies.
John Gage gets left with an trio of knife scars his captor said marked John as belonging to him in the Emergency! fic "Lost and Found''. The man's previous victims bore the same marks.
In the Blade films, vampire familiars (human servants) have the glyph of the vampire who owns them tattooed on their body.
In Captain Blood, slaves who attempt to escape and are caught are branded on the face with an FT for "Fugitive Traitor."
This is the reason the African mercenary decides to help the main characters in The Island. Their tattooed numbers identify them as clones - their lives to be thrown away for the benefit of their purchasers. He finds this uncomfortably reminiscent of the reason he was branded himself as a child, and decides to switch sides.
The tattoo number of a Nazi concentration camp Magneto from X-Men carries upon his forearm, which he has brought attention towards to serve as a reminder for human cruelty.
Combined with Scannable Man in The Terminator. Kyle Reece shows Sarah Connor the barcode laser-burned into his arm in the robot concentration camp.
In the Apocalypse film series movies Revelation and Tribulation, the Mark of the Beast resembles this, while in Judgment it is a coin-sized tattoo.
In the backstory of Django Unchained, both Django and Broomhilda have been branded with an "r" on their faces after an attempted escape.
In Honor Harrington, genetic slaves are marked with their identification number on their tongues. The ex-slave terrorists of the Audubon Ballroom have made it their trademark to stick their tongues way out to show off these marks to the slavers they kill.
Common on Gor. Slaves most commonly get the same stylized "K", called kef, standing for Kajira (or, very rarely Kajirus).
Brands are occasionally used for other purposes - the Caste of Thieves brands their members with a small mark on the cheek, for example. Qualius the blind Kaissa player has a kef on his forehead, but that was because of torture, not slavery.
The mark of slavery for house elves in Harry Potter is the lack of real clothes; most wear pillowcases and tea-towels and such. Being given clothes is equivalent to being freed...and usually regarded as a fate worse than death.
This makes perfect sense when you understand that house elves are normally freed only if their service is grossly inadequate, so being freed is normally a very grave condemnation of the very foundation of the house elf's self-image..
Robin Hobb's Liveship Traders trilogy has all slaves marked with tattoos, showing to whom they have belonged. Unruly slaves who've been sold many times are known as 'mapfaces', and the freed slaves take to calling themselves 'Tattooed' rather than 'ex-slaves'.
Slaves in The Stormlight Archive get a pair of glyphs branded on their forehead, slaves deemed dangerous get a third glyph shash which means "dangerous".
Slaves in Carol Berg's Rai-Kirah series are branded with a crossed circle, though many of them can be recognized racially as well. Runaways (and occasionally others) may also be branded on the face.
In Jack Chalker'sFlux & Anchor series, the male-dominated society of New Eden tattoos the rump of all new Fluxgirls, women bound into slavery (and perpetual ignorance) by magic.
The Roman Mysteries: Jonathon gets branded as a slave in The Assassins of Rome. The brand causes problems many times later when he has to prove that he is actually a free Roman citizen.
One of the made-up countries in Thomas More's Utopia cuts part of a slave's ear off as a permanent mark. Which promptly turns into Fridge Logic once the narrator says that slaves can not only earn their freedom, but a certain number are freed every year — so do they get their ear repaired? Or are they always at risk for being re-enslaved as a runaway?
In the Dragon Jousters series, only free men shave their heads or cut their hair. Slaves and serfs (an even lower class) wear their hair long as a mark of their unfree status.
Black Dagger Brotherhood gives us the vampire Blood Knight Zsadist; who sports pitch black bands around his "drinking points" (wrists and neck), from the time he was enslaved and sexually abused during the eighteen hundreds.
Zeturah, a novelization of the Book of Exodus, includes a scene in which Moses' sister opens her shirt to show the scars Egyptian soldiers gave her. She shouts, "Behold, the mark of a slave!"
In A Song of Ice and Fire, slaves in the east are tattooed on their face to show their specific occupation. Ser Jorah Mormont gets a special one for being rebellious.
In Les MisÚrables, Jean Val Jean views his 24601 number and brand as this. Technically it's to show that he's a criminal, rather than a slave, but in Revolutionary France the two statuses amounted to the same thing.
Discussed in an episode of Kung Fu: Caine is staying with a black family. The father (who had been in favor of throwing him out because he didn't want trouble with the town) sees Caine's tiger & dragon arm brands and assumes they're slave brands, since he (the father) had been branded when he was a slave. He asks Caine if he's a runaway slave.
Caine: I am a priest. Caleb: If you're a priest then who put those brands on you? Caine: I did. Caleb: It's a foolish thing for a man to put brands on himself. I'd give anything to be rid of mine. Caine: And I to keep mine.
The Jaffa of Stargate SG-1 have a mark either tattooed or branded onto their foreheads. The appearance of the mark is determined by which Goa'uld they serve. Note that this brand is a mark of honor: it signifies the Goa'uld in question's First Prime—the Jaffa head of his military forces. (Bra'tac was apparently Apophis' retired First Prime, hence the brand despite not being First Prime at the time). Lower-ranking Jaffa get tattoos done in black ink. The first episode also included some priests with silver-filled brands, but whether this is supposed to be a general trait of the Jaffa priesthood (whom we never really get to see) or just Early-Installment Weirdness is never made clear. The gold brand involves cutting open the skin on the forehead and pouring molten gold into the wound.
Thug: ...that sounds painful. Teal'c:[pins thug to wall] Excruciating.
Spartacus: Blood and Sand: The gladiators are branded with the mark of the House they belong to. Body slaves get a tattoo that points out their status as a body slave and who they serve.
The Blacklist Reddington goes after a human trafficking ring that brands its slaves. At the end of episode Reddington's male body guard is changing in the locker room you see the same scar on his shoulder.
In Alice (2009), humans who wind up in Wonderland have a light shined somewhere on their bodies that causes a tattoo to form. The Wonderland inhabitants refer to them as "Oysters" and typically round them up to have their emotions harvested. Alice gets hers on her arm and has to cover it up to move freely. It is still there when she makes it back to Earth, one of the things that proves her experience wasn't a dream.
In the "Ravnica" story arc in Magic: The Gathering, one of the ten guilds—the Orzhov, the Black/White aligned Corrupt Church, uses its guild signet (a black sun with twelve rays) to denote master (worn as jewelry) or slave (tattooed to a debtor).
In Exalted, sacrificing a living human in the name of a deceased human will cause the sacrificed to become a slave-ghost to the person they were sacrificed to. The ghost-body of the slave bears a special mark that will never disappear, even if body-altering ghost-magic is used. Special ghost-apparel that can hide this mark is highly valued in the Underworld.
Truth In Television
The numbers tattooed on the arms of Nazi concentration camp inmates. Not necessarily used to mark them as slaves but to keep track who each one was. Sometimes it determined their classification (besides Jews, a whole host of others were placed in the camps).
The tattoos were also intended to humiliate, since tattooing wasn't a common practice back then. It was a particular humiliation for Jewish inmates; tattooing is expressly forbidden by Judaism, and even relatively unobservant Jews would have never even considered a tattoo.
In ancient Israelite society, a Hebrew could only be the slave of another Hebrew for six years, and then he was to be released. If the slave refused to be released he was to have his ear specially pierced as a sign for someone who refused to be free.
This only applied to male slaves, however; women didn't get such luxury. That said, Hebrew slaves are always free to marry other Hebrew slaves, and the wives and children of Hebrew slaves are Biblically supposed to go free when the man does. Thus a Hebrew slave woman could marry a Hebrew slave man and win her freedom indirectly.
African slaves would occasionally be branded before being shipped to America.
Among BDSM lifestylers in a total power exchange relationship, branding is a considered mark and ritual of dedication by both slave and master. Strike branding, using a hot iron, is still preferred by most. Tattoos are sometimes used, if the master has the skill or a particular design that requires inked lines. A cold branding with liquid nitrogen is becoming more popular, as it requires a less practiced hand to get clean, lasting lines, and the result is less prone to infection.
This didn't keep the Romans from tattooing in relatively inconspicuous places for other purposes—for instance, exported slaves would have "tax paid" tattooed on them. Also, legionaries would have a tattoo on their hand for easier identification in case of desertion.
They also inverted it with the Phyrgian cap - a kind of hat given to freed slaves.
Red XIII of Final Fantasy VII has something kind of like that in his "XIII" tattoo. He was a research specimen; not much different from slavery, though Hojo probably wouldn't call it that.
In Dragon Age, casteless dwarves are marked by facial tattoos.
Tranquil mages (mages who have had their magical ability forcibly stripped from them) have a sun brand on their forehead, which is apparently a symbol of the Chantry. This is only actually visually present in Dragon Age II, but it is mentioned in the first game.
It also resembles a lobotomy scar, which is pretty close to what Tranquilization is supposed to represent.
Archipelago: Captain Snow uses this to keep unruly slaves or underlings in line. Including the protagonist.
The Transformers has the Autobot and Decepticon insignias originally being this; the two races originated as sapient consumer products, with the insignias being product logos forced on them representing whether they were military or models intended for general consumption. After they Turned Against Their Masters, they decided to keep their logos and turn them from marks of shame into badges of pride.