Virtually everyone has to wear a public mask in order to be accepted by others. That's a simple fact of human psychology. When circumstances (such as anonymity, strong emotion, or sufficient power) allow a character to take off that mask and act in complete accord with their inclinations, they reveal what's Beneath the Mask.
The secrets this mask hides are varied and are not always dark. A villain, for example, might be hiding a soft spot.
Sometimes a person may never know they had a hidden self before the mask comes off. The change is even a surprise to them. Other times the person is well aware of their hidden self and are determined to keep it hidden. This hidden self that people don't show to others is what Beneath the Mask is about.
This hidden self is sometimes portrayed as "the real self". Occasionally the person actually wants someone to see their hidden side (the "real me") but for some reason can never get people to see it. More complex works might argue that the hidden self is just a part of the real self, and that the public self is also part of the real self.
Related to GIFT and What You Are in the Dark. Often used in conjunction with Jerk with a Heart of Gold, Jerkass Fašade, Bitch in Sheep's Clothing, Sugar and Ice Personality, and The Proud Elite. Obfuscating Stupidity and Obfuscating Insanity can be subtropes, as can A Darker Me.
Not to be confused withHidden Depths or Rich Idiot with No Day Job, which are about skills and roles rather than personality. Compare and contrast Becoming the Mask, where the facade itself actually becomes part of the character's personality.
Sakura from Naruto is a perfect example: her inner side shows us what she actually thinks about something but is not willing to say or do. Although Inner Sakura hasn't been seen since the timeskip, and Sakura is now more willing to say what's really on her mind. A bit of a cross between Becoming the Mask and Character Development.
One theory is that Sakura broke out of her Stepford Smiler attitude and embraced "Inner Sakura" after it helped her break out of Ino's body switch jutsu during the Chuunin Exam.
Meditating at the Waterfall of Truth reveals the depths beneath Naruto's own Stepford Smiler habit. He had truly hated and despised the villagers who treated him poorly, and questioned the sincerity of their change of heart regarding him, but he buried those feelings deep down. Due to the Kyuubi's presence, they coalesced to form a split personality who would feel all the negative emotions Naruto refused.
This aspect of Naruto was hinted at early on when Karin encountered him and got a feel of his chakra. To her surprise, his chakra had three layers: a) Bright, Warm, and Comforting; b) Dark, Cold and Overwhelming; c) Corrosive, Chaotic and Sinister. The last one is from Kyuubi's; the first two polar opposites were Naruto's.
Played with in Itachi: The first time the mask "slips", he's crazily taunting his brother and showing obsession with power. It later turns out this was him trying to goad Sasuke into killing him, and doesn't resemble his real personality at all. It really turns out that he's a extremely Tragic Villain who despises himself his Necessarily Evil actions and loves his brother more than anything else in the world, even the love for his village that forced him into destroying the Uchidna clan. The Stoic personality, however, is just who he is; apparently he was born without the ability to express emotion.
Code Geass plays with this trope. Lelouch Lamperouge is a Brilliant, but Lazy highschool student living in Area 11, a Britannia-occupied territory formerly known as Japan. When we first see him, he's skipping class in order to do some high-stakes gambling. He seems to regard everything with indifference or disdain, and as we get to know him, it becomes clear that he has a strong sense of justice but has come to accept that there's nothing he can do to fix his government's deep-seated corruption and institutionalized racism. Then he gets superpowers. He maintains his Rich Idiot with No Day Job facade to avoid suspicion, but secretly becomes Zero, a masked freedom fighter dedicated to dismantling the most powerful government in the world. The series heavily contemplates identity and character, and repeatedly addresses the irony that Lelouch needs to put on a literal mask in order to take off his metaphorical one.
It should also be mentioned that in his conversations with CC Lelouch strongly implies that he was planing to overthrow Britannia since he was a child, gaining the Geass simply meant that he could start much earlier and move much quicker than he otherwise would have been able to. As such one can say that his hidden personality was already simmering in the depths of his lazy life before the story kicks in.
The manga version of Neon Genesis Evangelion pulled off a Type C with Asuka: she acted like the stereotypical good girl around Misato and Kaji while being a total jerk to everyone else. Once Misato revealed that she knows Asuka's true personality and she doesn't have to hide it, Asuka became a full-blown Tsundere with an extra helping of Hair-Trigger Temper.
In the anime, this is what Rei actually is, though initially, it appears she is simply an Emotionless Girl.
Kraehe is initially portrayed as doing things just For the Evulz, but by the end, it's revealed that she only wanted to be loved.
Beet The Vandel Buster has Grineed, who actually wears a literal mask (more like an extra outer skin) to keep himself calm and composed, instead of the raging beast that is underneath. Needless to say, Beet and the squad bust it out of him pretty quick.
Seems to be a theme in Durarara, where pretty much everyone involved, up to and including the district of Ikebukero, has a hidden second side beneath the personalities they show to the world.
Kurei from Flame of Recca personifies this trope, he even wears a mask! He may seem like one of the most cruel, heartless and sadistic characters in the series, but most of his actions are driven by his love for people he cares about.
Higurashi No Naku Koro Ni sort of plays around with this, where in first and last arc of the anime's first season the characters discuss social masks and not speaking about things they don't want to speak about, such as in the first arc, both Keiichi's and Rena's hiding their respective Dark and Troubled Pasts, and in the last arc, Keiichi hiding that he killed Rena and Mion in the first arc.
However, it's played more straight with Rika in the second season, where although everyone knows about her place in the Furude family, she acts like a child usually would at her age. At least, the age everyone thinks she is. However, when she's seen alone with Hanyuu, she acts much more like a stoic, or even a Determined Defeatist.
Barnaby Brooks Jr. from Tiger & Bunny has two masks superimposed on one another. The first is the guise of a charming, skilled ace that hides a rude, untrusting Ice King beneath it. The rude, untrusting Ice King mask in turn hides a traumatized, lonely man who doesn't know what to do with his life beyond getting revenge on the organization that assassinated his family.
Haruhi Suzumiya: Sometimes the only way to determine that Kyon has leaked a comment instead of internally snarking it is when another character responds to it. In addition the title character does not know that he's leading a conspiracy to keep her from her true abilities and so sees the silent snarking as silent support.
Also, ItsukiKoizumi is implied to have much more going on under his always-smiling, friendly, easy-going exterior than meets the eye, especially in those few moments when he slips up and lets a little of his anger, stress, or loneliness show. Confirmed in Volume 11 when he goes completely ballistic at Fujiwara for trying to kill Haruhi. Also, Haruhi takes him as her ever-loyal ally without realizing he is The Chessmaster behind much of what goes on.
Several characters in Life are like this, typically to mask their Jerk Ass side.
In Kimi No Iru Machi when Haruto first meets Eba Rin he wonders how such a level headed person could be related to Yuzuki, even if only as step-sisters. Eventually Rin gets tired enough of the mask that she completely discards it with Haruto, in fact she is more honest with herself around Haruto and eventually Yuzuki that she doesn't put it back on around them, leading her to change just a little bit.
Maho Nishizumi of Girls Und Panzer typically acts as an Aloof Big Sister to Miho. However, beneath that mask lies a kinder individual, who gets along well with her family maids, is willing to lend Mako her team's helicopter to help her visit her grandmother in the hospital, and strives to live up to being Nishizumi heir mainly so that Miho can live and do tankery the way she wishes.
In Toradora! Ami is, to her classmates, a cute, sweet, fresh-faced model that's a bit of an idiot. But to the people that know her well, she's stubborn, sometimes bitchy and actually quite manipulative. It's mentioned several times that she genuinely wishes people would accept her "true" self, but is afraid of how people would react.
Sasame from Prétear is outwardly flirty, cheerful and quick to offer up a listening ear, but is secretly struggling with bitterness and depression due to unrequited love. In the anime his mask eventually comes off after he more or less has an emotional breakdown, while in the manga his mask slips off occasionally, but he continues to try to keep up the act until the end.
The Sentry, though he pretends to be a Lawful Good hero, has a dark side that manifests against his will.
Jean Grey's Phoenix persona was retconned to be her actual innermost personality, not a separate entity. It is very different from her public persona.
The notion that it was a separate entity was itself a Retcon, and Phoenix was always supposed to be Jean Grey's more passionate, "dark" side. Mastermind's messing with her head was originally what made the "superpowered side" evil.
Inverted by Jack O'Lantern in Ultimate Spider-Woman: Change With The Light. Although he wears a public mask to be accepted by his fellow citizens, he also begins wearing a ghoulish pumpkin-headed costume and committing increasingly deadly crimes to reveal his true personality. He is well aware of the irony in wearing a mask to reveal his true face, but he considers himself superior to the pathetic, mindless sheep and cattle that make up most of the rest of society because he's willing to embrace just what he really is.
In DC Nation, Fauna lampshades this when it comes to Nightwing. After seeing him as Dick Grayson, she wrote in her Character Blog that not many people put a mask on when they want to be themselves.
Seen in a Danny Phantom Fan Fic called Masks In which Danny's double life has caused Mr Lancer to keep him in school for the entire weekend with Jack and Maddie's blessing in order to find out why he is slipping up so badly. One notable thing that the author does to expand on the superhero masks is that Danny is actually wearing three masks to hide who he is.
Shrek hides a soft spot too, particularly over his need of love.
In Tangled, Gothel appears to be a loving though overprotective mother towards Rapunzel. But when Rapzunel finds out she was the lost princess and Gothel had kidnapped her all along, she reveals her true greedy nature that she would do anything to keep Rapunzel's power to herself even murder.
Flynn's daring, thieving personality is also a mask. As well as everyone at The Snuggly Duckling.
Enter the Dragon: In reference to Han, the villain, whose martial-arts tournament is a front for a really nasty operation: "You must remember... the enemy has only images and illusions, behind which he hides his true motives. Destroy the image, and you will break the enemy."
The basic premise of The Mask is that putting on the mask unleashes your id, not only making you act like you've always wanted to, but do anything you want, cartoon physics and all.
"It's like it brings your innermost desires to life. If deep down you're a little repressed, and a hopeless romantic, you become some kind of love-crazy wild man."
In Pirates Of The Caribbean Tia Dalma initially helps and even cares for Jack Sparrow, but in the third movie it is revealed that she is actually Calypso, a sea goddess. When she regains her full powers she becomes a destructive force of nature who doesn't care much about the various factions' petty struggles.
The knights' elaborate, mask-like helmets in the John Boorman film, Excalibur, show the real personae of the wearers.
A major theme of Wild Things. Sam appears to be an honest, upstanding educator, but he's really a sleazy, exploitative pervert. Kelly appears to be an all-American teenage girl next door, but she's actually an angry, sexually confused cokehead who hates her family. Ray appears to be an honest if overzealous cop, but he's actually a Dirty Cop who enjoys prostitutes and is quite willing to murder anyone who pisses him off. Suzie appears to be a white-trash loser, but she's actually a brilliantly calculating Chessmaster who manipulates everyone else.
Lampshaded by Ray, although in reference to another character.
Ray: People aren't always what they appear to be, Jimmy. Don't forget that.
Psycho - everyone, the hard working secretary who isn't, the local cop who pulls over a woman for speeding, but really they are role-playing for a more intimate encounter, everyone. Especially, of course Norman, who is really only a more extreme case.
In Twilight, Rosalie Cullen. Though she seems superior, emotionless and shallow to Bella at first, it is revealed that she actually envies Bella and is very much capable of deep feelings, loving her family, and being sad on the inside because of her inability to get pregnant.
A Soulgaze is a one time per person link. When initiated by the wizard staring into someone's eyes for a few seconds, each sees the other's True Self.
The Sight shows the essence of how things are — magical workings and their aftereffects are visible, people's mental and emotional trauma and strengths, etc. Anything seen with the Sight is permanently etched into the wizard's brain.
In Elias Canetti's book Crowds and Power, he speaks in detail about masks and hiding of a true-self in relation to power. For Canetti everyone wears a mask and for this reason a ruler is never able to truly trust in anyone, which is a cause of paranoia regardingbetrayal. For Canetti the "unmasking" is crucial in the movements of power.
John Le Carre takes a very dark look at this in the Karla trilogy. The protagonist, George Smiley, appears to be a slightly myopic, helpless, and generally tragic old man who is genuinely sick of all the betrayals and lies that constitute his profession and that has wrecked his personal life. Only occasionally do we see why he's still in the Circus: he is brilliant and very, very good at what he does, i.e., the betrayals and lies that constitutes the intelligence life. His opponent, Karla, appears to be an iron-willed fanatic for whom taking advantage of the opposition's humanity is part of the job. It is not until Smiley's People that we see the crack in his mask: his love for his illegitimate daughter, Tatiana, who is driven insane by her inability to recognize the spymaster as her father. The ending of Smiley's People implies that beneath their masks, Smiley and Karla are Not So Different - a revelation that drives Smiley to retire for good.
In The Gun Seller, the protagonist notes that a certain revolutionary leader puts on a different mask for every member of the cell. To one true believer, he's a fiery and passionate Che type; to the Southern hick, he's a rock and roll adventurer; to another, he's a philosophical seeker after truth. His true self is only hinted at when he instinctively strikes a small child on an airplane.
Double Subverted in Deep Space NineSoldiers of the Empire. Klingons underneath their swagger are lonely overworked soldiers grumbling about their lot just as much as human soldiers do. But when inspired they put on their mask again and go into battle as a true Proud Warrior Race.
Joan Foster muses on this in Lady Oracle by Margaret Atwood: having reinvented herself several times in her life, she's not particularly interested in seeing what's beneath the facades of the people she encounters, having decided that "facades were just as truthful" as what they hide.
Lana Lang once received Clark's superpowers, using them to try to kill Lex, steal his secrets, and discredit him in the media.
There was an episode with a flower that made people act out their secret desires. There was also the red kryptonite for Clark.
Niska in Firefly is fond of quoting the mad Chinese philosopher Shan Yu, who once said "Live with a man for 50 years, share meals, spend every waking hour with him. Then one day take him and dangle him over a volcano's edge, and on that day, you will finally meet the man."
House certainly thinks that this is humanity's natural state, given his famous quote "...Everybody lies".
This is a premise of the show too , as all the main cast including the patients are not always what they seem to be, in the case of the patients their lies often complicate the medical procedures of the team , while House himself dedicates his time to discover the secrets of his co-workers.
Lizzie McGuire displays the title character's duality with an animated version of Lizzie saying whatever Lizzie is really thinking.
Thomas Barrow on Downton Abbey is manipulative, dastardly and downright cruel, but whenever his mask of indifference and rudeness slips (usually on occasions involving death or spurned affections) he's shown to be a lonely man desperate for affection and to actually have something resembling a heart.
The Doctor, in Doctor Who. Yes, he wears celery, offers people jelly babies, and has a fascination with Cool Hats; seems like another harmless eccentric fellow, right? Yeah - that "harmless eccentric fellow" can quite literally tear the heavens asunder and reshape reality if he really feels like it. Still want to piss him off?
To add to this trope, despite the Doctor and his silly gimmicks, the Steven Moffat era has made it quite clear how much the Doctor hates himself for some of the difficult calls he has to make.
In iCarly, Nevel is a polite, nice kid when within his mom's vicinity, but is a complete Jerk Ass outside of it.
The Centauri in particular, as Londo confides to his lover Adira:
We Centauri live our lives for appearances. But when a I look beneath this mask I am forced to wear I see only emptiness. And then I think of you, and I say, "To hell with appearances."
In Wizards Of Waverly Place, behind her facade, Alex is insecure, dependent, and scared teenage girl, who desires to be accepted (somewhat by her peers and definitely by her parents, but mostly by Justin).
Harper's facade. Throughout the series, we see glimpses of truth where she hints at things that...are rather depressing for a kid's show...
In Real Life, David Henrie, Selena Gomez and Jake T. Austin are almost the opposite of their characters, Justin, Alex and Max Russo. In the show, Justin is actually The Klutz and an uptight Hollywood Nerd, while David is laid-back, boisterous and supportive, inclined towards the cool guy type, Alex is a Manipulative Bastard and apathetic Anti-Villain, whereas Selena is really nice, vibrant and open, and Max is a big idiot, dumb enough to misspell his own name, while Jake is smart and studious, much more serious than his cast mates, as seen in most interviews. Selena and David even impersonate each other in a live talk show, and the difference between the representations of their real personalities and their characters' personalities is quite striking.
Lady Gaga's song "Poker Face" is about this; the title refers to how it's customary to mask emotions as much as possible when playing poker to avoid giving anything away.
Electric Six has stated that they play disco dance music because it's "exactly what we are not."
Pink Floyd sang of this trope in their song In the Flesh: "So ya, thought ya might like to go to the show/To feel the warm thrill of confusion—that space cadet glow/Tell me, is something eluding you, sunshine? Is this not what you expected to see?/If you wanna find out what's behind these cold eyes, you'll just have to claw your way through this disguise!"
Britney Spears's "If U Seek Amy" video shows off how conflicting public and private selves can lead to confusion in the media. How certain people put on an act to maintain a fanbase or a group of supporters.
The song "Mr Roboto" by Styxuses this trope. "I am the Modren man/Who hides behind a mask/So no one else can see/My true identity."
Billy Joel's "The Stranger" is about what a person is beneath the mask. "We all have a face, that we hide away forever / And we take them out and show ourselves when everyone has gone..."
He gets pretty cynical about it. The song is about how no matter how close you are to a lover, there are some secrets you never tell, and you shouldn't be surprised if they're hiding their nature from you - because you're doing the same to them.
Adding the qualifier: "We may never understand how the Stranger is inspired / But he is not always evil, and he is not always wrong."
The Beatles' "I'm a Loser" : "Although I laugh and I act like a clown / Beneath this mask I am wearing a frown"
Boyce Avenue "More Things to Say" : "All we know is the mask and not your face"
Explored deeply in Jekyll and Hyde, most notably with the song Facade and its numerous reprises.
There's a face that we wear in the cold light of day/ It's society's mask, it's societies way/ And the truth is... That it's all a facade.
Fiyero in Wicked pretends to be a carefree, "brainless" playboy, but there's more to him than meets the eye, as Elphaba reveals after they rescue the Lion cub. Cue the beginnings of Character Development.
Elphaba: You could have just walked away back there.
Elphaba: So no matter how shallow and self-absorbed you pretend to be—
Fiyero: Excuse me! There's no pretense here. I happen to be genuinely self-absorbed and deeply shallow.
Elphaba: No, you're not. Otherwise you wouldn't be so unhappy.
A classic case is Squall from Final Fantasy VIII. On the outside: cold, cynical, mean, rude, and very much a Determinator. On the inside, he is collapsing: constantly questioning himself and why he continues to do what he does, and cripplingly insecure about how other people perceive him. He uses his anti-social exterior to hold others at arm's length rather than risk the pain of rejection or loss because such feelings devastate him.
We all wear masks because deep down inside we are nothing but beasts. The question I ask you is, to which do you submit—the mask, or the beast?
In Halo 3 the normally calm Prophet of Truth shows his true colors as a mad alien willing to kill his fellow prophets and an entire race of aliens while trying to reach godhood. This is a result of Becoming the Mask; in Contact Harvest, Truth doesn't come off as particularly pious and initiates the human-Covenant war to conceal humanity's status as 'Reclaimers' and gain control of the Covenant. He's been lying for so long and with such conviction that by the time he dies, even he believes his lies.
Both Guilty Spark and Medicant Bias hid their true intentions until their betrayals due to rampancy.
Gravemind acts as a calm, pragmatic, smooth-talking individiual with a high love for poetry, but when Master Chief is penetrating the Flood's defences at High Charity, Gravemind slowly shows himself as the ragefilled, angry, ruthless, hot tempered, screaming, murderous monster he actually is.
Persona 4 in particular is all about what we have behind the mask and facing it.
Zevran in Dragon Age: Origins appears to be a smartmouthed skirt-chaser, but closer inspection reveals a mess of homesickness and guilt.
Isabela in Dragon Age II has got an honorable side buried under all the greed and selfishness, and under her carefree sex-without-attachment persona she just wants to be loved.
Implied with Aveline and her tough-as-nails guardswoman persona. She's a very private woman who refuses to elaborate on her feelings and regrets after losing her husband, and has a similar attitude towards the party after she remarries.
Hawke, if played with a sarcastic/charming personality, acts flippant and irreverent to mask deep-seated feelings of loneliness, due to all the loss they endure over the course of the game. Their status as a Sad Clown is even more noticable after the murder of their mother.
A bittersweet one for Kings Quest: despite his return to Daventry, his rank of prince, and his joy of being a free man with a loving family, Alexander considers that identity as "a cloak." The Kings Quest Companion establishes that he still considers himself to be "Gwydion," the name he had as Manannan's slave. In the series guide, he makes a concession to both identities by signing his name Alexander-Gwydion.
Laharl from Disgaea tries his very best to be completely perceived as an evil demon, but his more positive qualities, like his forgiving, noble and strangely kind nature, is regularly provoked to the surface throughout the game.
Zelos from Tales Of Symphonia at first appears to be a Skirt Chasing pervert who uses his rank as the Chosen to bring Ladies to his bedroom and simply just relishes the limelight. Inside, he's really a calculating individual who suffers from self-loathing due to an EXTREMELY messed up childhood, which involves his mother telling him "You Should Never Have Been Born" just before she dies.
Tales Of Legendia: Grune starts of as an Amnesiac who is basically the teams personal Cloud Cuckoolander. Later on, even though she tries to hide it when she figures it out, it is revealed that Grune is really a goddess of time whose only purpose is to battle with her evil counterpart in order to determine the fate of the world.
Tales Of Vesperia. After his Face Heel Turn and subequent redemption we get to see the person behind Raven's sleazy-selfish-pervert mask. After revealing, he does return to the mask though, because he much prefers that persona.
Several characters in Liberty's Crusade would discuss what Mengsk could be like under the mask - as Kerrigan points out, he's unreadable. When Raynor calls him out on sacrificing Kerrigan, he engages in his well known tirade prompting Liberty to remark that Mengsk has finally shown his true face: that of a power crazed madman.
Throughout the Mass Effect series, as the commanding officer, Commander Shepard is forced to constantly show an air of calm, confidence, and no fears or worries. As Mass Effect 3 goes along, this mask begins to crack more and more, as s/he is slowly broken down by the pressure of stress of having an entire galaxy on his/her shoulders, and begins to show a great deal of worry, fear, exhaustion, loneliness, and begins to question whether s/he can actually pull it off and defeat the near unstoppable threat of the Reapers.
There's a moment in the Borderlands 2 DLC Mr. Torgue's Campaign of Carnage where Mad Moxxi makes some innuendo that relates cunnilingus to literal cannibalism, and manages to disgust herself. She apologizes and says that her innuendo talk is "just a defense mechanism" and her part of the radio goes silent for a while.
Bastila from Knights Of The Old Republic is arrogant, bossy, and Holier Than Thou about being a Jedi. However, she adopts this attitude because she feels enormous pressure to be a perfect Jedi, because of her rare Battle Meditation ability and the crucial position it puts her in despite her youth.
In the Ace Attorney series, we have Dahlia Hawthorne. She seems so sweet and innocent. She actually has the most intended murder victims, at seven. One of which was Phoenix himself. She is a very nasty person.
Lesteena in Eien No Aselia isn't sure whether her normal personality or the one she pretends to be when she gets a chance to relax is the real one. The answer seems to be both and neither.
Tohsaka in Visual Novel/Fate/stay night is a bit of a funny example. She acts like a perfect and kind student, but beneath that she's irritable, dishonest about her feelings, Not a Morning Person, selfish and something of a troll. However, beneath that is something she doesn't seem entirely aware of: She values people's lives a great deal, will die for others, values fair play and honesty and is actually rather kind. Nor is she as ruthless as she thinks she is.
In Sunstone a recurring theme of the webcomic is masks and how despite the fact these characters use persona in their BDSM, beneath these masks they are all perfectly normal (and in Ally's case Adorkable) people.
Tower Of God: Lero-Ro. He is actually quite angry about some of the decisions his boss Yu Han-Sung makes and how things work in Evankhell anyway, but manages to hold his criticism back and presents himself in a calm demeanor.
Rachel. She acts like she still is Baam's friend, but in truth she already sold him out for her own dreams.
To the new characters introduced in Season 2, Baam. He acts like an emotionless sociopath who won't hesitate to kill or fail everyone to pass the floor tests but that's because if he fails any of these tests, one of his friends will be killed by FUG. And he'll only know how many of his friends survived when he reaches the top. Which makes it even sadder because while the readers know that at least some of his friends are still alive, for all he knows, they could already have been killed (by the fierce competition in the Tower or by FUG) and he's doing everything for nothing.
Vriska in Homestuck tries with all her might to live up to the example of her famous ancestor, Marquise Spinneret Mindfang, preferring that everyone view her as the Spider8itch than risk showing a hint of weakness. Even she doesn't realise this until she kills Tavros, and either sadly or happily depending on your opinion of the character, it's too late.
Both Dr. Horrible and Captain Hammer actually have three layers to them. On the surface, Billy is just Billy, leading a normal life, trying to woo Penny, underneath that he's the power-hungry Dr. Horrible, but even deeper down he's just Billy. As Penny mentioned, she first thought Hammer was just a big jerk, but he became really sweet later on. However, he really is just a Jerk With A Heart Of Jerk.
Ask That Guy With The Glasses is a nicely layered version of the trope. The "mask" is a distinguished gentleman, underneath that is a bastard who likes playing with people, underneath that is an invoked Complete Monster, and underneath that is a cesspool of self-loathing and damage.
Iron Star of the Whateley Universe. He's a hero in the Future Superheroes of America club at Superhero School Whateley Academy. He's really a massive jerk who is in the superhero game for what he can get out of it. He's already stringing along three different girls in the Future Superheroes of America club and who knows how many elsewhere.
In Worm, Rachel Lindt, also known as the supervillain Bitch, is about as violentlyantisocial as a human being can get ... because her powers have overwritten her ability to parse normal human interactions with canine social instincts. As her Interlude reveals, given the choice, she actually wants to have friends — she just doesn't know how.
Toph Bei Fong pretends to be a weak well-mannered girl in front of her parents, but is a very powerful Earthbender and much more informal with her friends. Sometimes Played for Laughs.
Princess Azula infamously pretended to be a secure, strong, cold woman. It was revealed in the last episode that she was a lonely woman that wanted someone to trust, but lost her friends and didn't have anyone to confide in, and was crazy and sad because she wanted her mother's approval. It wasn't a coincidence that when she became more powerful thanks to nearly becoming the new Firelord and getting a power upgrade that it became too much for her to handle.
Prince Zuko as well, especially in season one. He is introduced as a ruthless, conceited bully of a prince who only cares about himself and seemingly looks down on everyone, including his superiors. In reality, he's just a good-natured kid who wants his father to be proud of him. Over the next two seasons, this facade begins to gradually break and by the final episode it has disappeared completely.
Helga from Hey Arnold expressed her true feelings for Arnold when alone.
Before Flanderization kicked in, Trixie Tang from The Fairly OddParents was secretly a tomboy that liked comic books and disguised herself as a boy because she had fear of being judged and rejected due to the fact that she is a popular girl and the Alpha Bitch of her school.
Candace Flynn is secretly a fan of a series called Duckie Momo (a parody of both Hello Kitty and Pokemon). She used to wear a costume in order to hide her love of the series from her friends, going as far as lying to both her boyfriend and her best friend.
Isabella has a hidden crush with Phineas, something both Ferb and Candace are aware of. However, in front of him she pretends to be Just Friends.
Perry the Platypus acts as a non-sapient animal (where it is not uncommon for someone to claim. that because he is a platypus, he doesn't do much), but in reality he is a very skilled and smart secret agent.
Suzy, the sister of Jeremy, pretends to be a dumb innocent girl, but in reality she is very smart, and cruel to whoever threatens her relationship with Jeremy.
In Teen Titans Raven keeps her emotions largely in check, rarely expressing any sentiment more passionate than a sarcastic quip. Then the episode "Nevermore" gave her a Journey To The Center Of The Mind, where we got to see all the different sides of her personality. One side is perpetually depressed and endlessly apologizes for all the mean things she's said. Another side is a Blood Knight who just loves to fight. Another is a gigantic demon made of pure rage. And, most disturbing of all: a perky, giggling Raven who loves the color pink and thinks Beast Boy is funny (something Raven would normally rather swallow her own tongue than admit to).
Vlad Plasmius has a facade of being a nice guy in front of the Fenton family (except Maddie) and the general public by being a well-known billionaire and later mayor.
Danny Fenton had a facade of indifference and naivety over his secret identity in front of his sister and his parents. This was mainly to protect them.
Dash's best friend, Kwan, has a facade in other to be accepted among the popular crowd. Deep down, he is insecure and unsure about the things he does (bullying and whatnot).
The Flash in Justice League is about the only character who wears a literal mask, but not a metaphorical one. He's the same fun-loving guy whether in or out of his civilian identity.
Artemis in Young Justice definitely has a facade, as Red Arrow points out. She is even willing to let a villain escape because of it.
As does Impulse. His personality during his introductory episode is more or less an act that he uses to hide the fact that he comes from a Bad Future.
Kevin Spencer, in his confrontation with Love InterestShawna, states that beneath all her sociopathic, murderous tendencies, she's really a popularity-obsessed bitch.
Casper the Friendly Ghost, in one of the older cartoons, Fright from Wrong, is force-fed a huge jar of "Mean Pills" by his mean uncles, who want him to be a mean ghost to humans. But Casper spends the rest of the short putting them through the wringer (both literally and figuratively). It would appear that this example wouldn't count since Casper was drugged to act like that, right? Ehhh, not so much... he reveals at the very end that he never took the pills; all the cartoonish brutality he'd unleashed on his uncles was all him just trying to teach them a lesson! The little Friendly Ghost has a vicious side hidden under the "friendly".
In Thundercats 2011Rascally Rabbit the Drifter is an always smiling, Brilliant, but Lazy man who's facade is one of carefree, perpetual mild amusement. In actuality, he's deeply depressed and grieving a personal loss, to the point of fixatedly attempting to save others from duplicating his mistakes by delivering Adventure Rebuffs and an unending stream of unsolicited advice, all the while peppering his speech with his insistant "I don't care."
The Rorschach test is a test that psychologists use to find insights into an individual's personality through their interpretations of ink spot patterns.
In astrology, your birth or "sun" sign represents your inner personality (based on time of year), while your outward personality is supposedly whatever sign was coming up on the horizon at the time of your birth.