Atoli in .hack//G.U. Games is cheerful and bubbly, wants everyone to get along, and wants to be loved... and then you find out she's like that only because her total lack of self-esteem in real life, due to lifelong emotional abuse by her parents ("Girls should be quiet and unnoticeable!!"} and bullying by her schoolmates led her to browsing suicide websites where she met and found comfort in the player behind Sakaki, who was really only using her in order to assume control of Atoli's Epitaph, Innis the Mirage of Deceit.
Aerie in Baldur's Gate II is Depressed. She’s very depressed due to a traumatic past, but tries to look cheerful despite for it.
Barbie from Barbie Super Modelnever stops smiling, although she seems to just be genuinely happy all the time. This isn't too surprising since the game was based on a franchise of dolls with painted-on smiling faces.
Litchi Faye-Ling from BlazBlue is Depressed. On the outside and towards the people of Orient Town, she is highly sociable, kind, compassionate and caring doctor who is idolized by pretty much everyone, and it might not be a lie at all, she's deep down kind hearted. However, she never told anyone about her own problems, that being a desperate lover with Guilt Complex, especially for letting her lover turn into an Eldritch Abomination, injects herself with the same corruption which granted her power and looking for a cure and in the same time rotting her body away, and she'd rather bear the burden herself than worrying those she cared about with it. Hazama managed to find out her face behind her smiler face and used that to manipulate her to get her Forced into Evil under the guise of eventual survival from the escalating corruption and the chance to cure that lover. Which in turn, made her pull a new mask in front of Rachel: She pretends that only her lover needs help and she's the only one who can, while in truth, she also needs help as well when the other source of help (Kokonoe) flat out refused to help. Unfortunately, Rachel bought that mask and dismisses her as an obsessed idiot who chose the wrong side.
Haru from Devil Survivor. Behind her typical idol singer personality lies a suicidal depression.
Yuna from Final Fantasy X plays with this trope in a very interesting way: it's made very clear that she deliberately takes on the role of 'heroic savior of Spira' so as to inspire hope in the rest of the world even though she's much more scared and sad than she lets on, but it's not just a simple matter of her putting on a totally fake mask. In the infamous laughing scene, Yuna admits that she tries to smile even when she's feeling sad, and the more she does it the less sad she feels. Sure enough, as she encourages a reluctant Tidus to force himself to laugh with her, they end up actually falling over each other laughing at how ridiculous the whole thing is. So Yuna definitely does pretend to be much more happy, confident, and perfect than she actually feels, but to her it's less about putting on a mask as deliberately turning into that kind of person inside and out.
Vanille from Final Fantasy XIII is a perfect Depressed example. Her unnaturally happy and positive attitude was just a way of running away from her past failures. She has an authentic death wish and blames herself for everything that has happened.
In Fire Emblem 7, the Cleric Serra is a mix of Genki Girl and Rich Bitch who acts like a princess... but truly is an orphan dropped at a small, miserable Ostian convent by an Etrurian clan in danger of being wiped away. Her parents never came back for her and she was badly traumatised by their abandonment. Get her to support with people like Hector or Lucius to get more details.
Generally subverted with Nowi from Fire Emblem Awakening. She chooses to spend her days being happy rather than being depressed by the fact that she will outlive all of her friends, but despite how she hurts over the eternal life deal (due to her manakete dragon blood), she never really hides her pain.
Peri from Fire Emblem Fates is a mix of 1 and 3, being mentally disturbed due to having her mother murdered by a servant when she was still a child, and seems as happy as possible during fights to distract herself from her sadness.
Daniella/The Maid from Haunting Ground certainly qualifies; for her first few appearances in the game, she is polite and courteous to Fiona, only to reveal her truly Ax-Crazy nature during the game's second act.
Miranda Lawson from Mass Effect 2 keeps trying to convince herself and everyone around her that she's happy and she's found her place in life, but that perpetual smile of her just screams "Fake!"
GLaDOS from Portal. At first, she seems to be just a rogue AI gone insane, but the sequel develops the character further when you get to see the history of Aperture Science. GLaDOS used to be a human being that worked as a secretary named Caroline for scientist Cave Johnson. Johnson made it where after he passed on, he wanted the facility to be maintained under Caroline's control via uploading her mind to a computer. This made Caroline become GLaDOS where she would be forced to run tests in the name of science. Forever. It's understandable why GLaDOS would snap and start to actually like testing subjects just for the sake of testing because it was all she was made for and nothing else. When GLaDOS learns of her past, she actually becomes afraid of herself knowing that she used to be a person with emotions and feelings and that she can hear her own thoughts instead of ones programmed into her. In the ending of the game, GLaDOS seems happier knowing she saved Chell's life, but she then reverts back to her cynical and somewhat unstable self because it's all she is used to.
Carol in Mitsumete Knight. She became this because she was frequently bullied in her childhood and had no friends. She posed as a Genki Girl in order to remedy this, and sadly this worked all too well.
Sagiri from Suikoden V was trained to be this kind of character, a ruthless killer with a permanent smile on her face. By the time you meet her she's mostly rehabilitated, however she still finds herself unable to adopt any other expression.
In System Shock 2 you find the protocol droids, robots made to work like secretaries, greet people, give directions, etc. When they turn against you, they walk around searching for you, saying things like "Where are you, sir?" "I cannot help you if you keep hiding. "Please wait, I can offer you my assistance.". When they get near to you, they FRIGGIN EXPLODE.
Colette from Tales of Symphonia is a Stepford Smiler, always having a smile on her face, even as she starts to lose her humanity and later on starts slowly turning into a Cruxis Crystal while trying as hard as she can to keep it a secret from everybody.
Touhou: Empty. Koishi Komeiji is a cheerful child outside, but she's as hollow as possible inside- she's close to the state of "no-mind" according to Buddhism. Confirmed by the local Buddhist nun Byakuren.
Shiki from The World Ends with You has this as she tries to pretend to be her bubbly best friend because she feels the real her is worthless.
In The Legend of Heroes: Trails of Cold Steel, Millium Orion is perhaps this to some degree. If you see her bonding scene with Rean, she reveals that it isn't all fun and games. She's presented as a Genki Girl with a love of stuffed animals and seemingly boundless energy, but she's also a government agent and everything that comes with it, and sometimes she feels like there's two of her. She never even got to attend Sunday School. To at least some degree, the whole perky happy-go-lucky girl thing is an act.
Luxanna 'Lux' Crownguard is a seemingly chipper girl-next-door prodigious mage in service of Demacia and seems content in serving the nation (considering it also has her brother Garen). During 'League Judgment', a test to see if a candidate's worthy of being a champion for the League of Legends, it's revealed that Lux actually joins the League because she feels empty, being dragged into military service against her will, dragged away from home in tears, completely exhausted Lux's mentality and at this point, joining the League is all she had in life. This creates an eerie dissonance with her usually Annoying Laugh that players tends to abuse, because it can be easily misinterpreted with Lux snapping and Laughing Mad.
Sona Buvelle is at first an innocent, gentle-hearted and sweet Cute Mute musician, always trying to keep her fans content with her music. There's just one thing the fans didn't know and also revealed in her League Judgment: Her musical instrument, Etwahl, just refused to be separated from Sona, and the last time her beloved stepmother Lestarra tried to claim it... the instrument killed Lestarra with Sona unable to do anything because she's mute. She claims that she's trying to discover the extent of the instrument's power, but it's quite clear that Lestarra's death continued to haunt Sona despite her usual gentle demeanor.
Nessiah is a combination of Depressed and Unstable in Blaze Union; his gentle and polite demeanor hides a thousand years' worth of pain, suffering, and Sanity Slippage.
Shade in Borderlands 2: Captain Scarlett and her Pirate's Booty, is most definitely not the only living person in Oasis! He's rigged up the bodies of a few people with crutches and speakers, posing them in "lifelike" positions and using pre-recorded ECHO tapes to create the illusion that they are still alive and capable of meaningful social interactions (he's either not aware of or willingly ignores tape malfunctions). He even went to the trouble of recording a rejection to a marriage proposal. He doesn't want the Vault Hunter to leave so soon, before they've gotten to know each other, but he can't really stop them (both because he's a dehydrated, delirious civilian compared to an armed and armored Vault Hunter and he's a quest-giving NPC so he can't leave his booth). Upon learning that there was an underwater cavern filled with water directly under Oasis, he descends into tragic laughter.
Hope is implied to be Depressed in Final Fantasy XIII-2. When Serah and Noel first meet him, he mentions that everyone he was friends with disappeared from his life immediately after the fall of Cocoon. Becomes more explicit in Academia 4XX - Hope sends himself on a one-way trip 400 years into the future because his father had died and there was nothing left for him in his own time.
Forde from Fire Emblem: The Sacred Stones. He states in one of his supports that he acts cheerful and relaxed mostly to keep his friends and companions happy in the middle of the war.
Henry from Fire Emblem Awakening. It's readily apparent that he's not quite right in the head due to the fact that he's always smiling, even when talking about morbid subjects like torture.
His type of Stepford Smiling actually depends: the Japanese version he's a straight Depressive pretending to be Unstable. The English version is rather unclear on the issue, though it seems to lean more toward Henry genuinely being exactly as cheerful as he says he is with a side order of crazy along for the ride.
Libra as well. Tharja is actually disturbed when she finds out exactly how dark his soul is due to his Dark and Troubled Past. Specifically, being abandoned by his parents because they thought he was possessed, leaving him homeless and alone until he found shelter in the priesthood.
Inigo is a straighter example. His father wonders how he could be such a Pollyanna when he came from a Bad Future. This prompts Inigo to snap at him, explaining that he's that way to keep the others' spirits up.
Creepy Child Chris from The King of Fighters fits this trope very well, as he's almost a modern version of the aforementioned Soujirou. Always with a smile in his face, even when killing random people. The fact that he's the Big Bad's host doesn't help, either.
The Legend of Zelda: Majora's Mask has the Happy Mask Salesman: He seems to be generally happy, but come back to him without the money you owe (or without his stolen mask) and his broad smile turns into a furious grimace as he starts threatening you.
Shorty in Nancy Drew and the Secret of Shadow Ranch acts like a pleasant, cheery person right up until the end, where it turns out that he's the ringleader of a gang of criminals responsible for several acts of robbery and sabotage, and is perfectly willing to kill and deceive to get what he wants.
Also Kou, one of the social link characters, fits Depressed. Meanwhile, Teddie is Empty. He gets better.
Yosuke could also be seen as Depressed, according to his Shadow.
It also has Nanako, the protagonist's cousin, and Rise who are both Depressed.
The protagonist himself can come off as one as well, if one opts to max out all Social Links in the same playthrough.
Zelos from Tales of Symphonia is a Stepford Smiler, as he struggles to hide a truly twisted past behind a mask of frivolity and promiscuity. At certain points of the story he offhandedly hints about his past, before laughing whatever he said off as lies or changing the subject. Whether he's lying or telling the truth is left to the viewer, unless they go out of their way to see a cutscene where he openly reveals his past to the main protagonist.
Another example is Jade Curtiss from Tales of the Abyss. He does it due to being The Stoic, and to mask feelings of guilt and inadequacy over accidentally killing his teacher, then spending nearly ten years cloning her over and over again, only to kill the faulty clones when they failed to have her memories and thus truly be able to replace the mentor he'd lost. Plus, it helps a Deadpan Snarker to keep a straight face.
Easier to miss is Guy Cecil, born Gailardia Galan Gardios of Hod and heir to the title of Count, whose family was killed by Luke's father when he was only a small child, and who has spent the years since then acting as a servant in the Fabre household and planning to kill them all as revenge for his family's death. He gets better as the game goes on, but some scenes still clearly show that he has anger issues hidden very thoroughly under that cheerful smile.
Burgerpants from Undertale. His face changes between several wildly different Ren & Stimpy-esque smiling expressions, all while he talks about how his life has gone downhill and his job is terrible.
Laid-back and pun-loving Sans is also revealed to be this during a "No Mercy" playthrough; he realized long ago that his life is determined entirely by the whim of somebody else (namely, the player) and can be reset without warning at any moment. He admits that it makes finding motivation to do anything difficult, and that at this point, even making it to the surface world (which is what all monsters want and the main goal of the "Pacifist" route) doesn't appeal to him anymore because it would feel like a set up for a Hope Spot. Exactly how depressed he truly is depends partially on player interpretation, and on how the player decides to progress through the game. He's a more literal example of this trope, as he doesn't crack a frown once the entire game, even managing an extremely Broken Smile if you kill him.
Papyrus, ofallpeople, becomes this in the Neutral ending in which he becomes the new monster king. Said ending necessitates killing off a brace of important Underground residents, including Undyne, who is Papyrus's Only Friend other than Sans; in his and Sans's epilogue message, Papyrus says he's been his usual cheery and optimistic self in an effort to bring morale back up among his new subjects, but he admits it's been difficult and that he misses Undyne.
Mixed Gender Examples
Any game from Zynga. In Cityville, it's just getting scary with how everyone always smiles and looks so cutesy. Some people have named their cities Stepford for this very reason.
Given that it's set in The Fifties, many civilians in Destroy All Humans! fall under this heading, particularly the residents of Santa Modesta. Quite naturally, these suburbanites like to present themselves as flawless and content, but a quick peek at their thoughts reveals that the men only manage to suppress their psychotic rage with their collective obsession with lawnmowers and automobiles, and the valium-addicted women are engaged in fierce and unending competition over the best home and garden, broken only by tupperware parties and neglected children. Exactly one citizen manages to realize how miserable she really is, and in the end, she decides to drown her sorrows in cheap meaningless sex. And of course, being an alien invader, you have the opportunity to put every last depressive one of them out of their misery in the most painful way possible.
There's a whole town of Stepford Smilers, well-groomed but down-to-earth, assured Andale is the best little town, that their blessed country will protect them from the commies, and that all is right with the world. This being Fallout, of course, things find room to go downhill.
There's a woman in the small town of Arefu who seems to have gone completely delusional and pretends that she is living in a beautiful pre-war suburb. She hands the player rusty tin cans, proclaiming they're her prized batches of chocolate chip cookies. Ironically, she's never even experienced life before the war.
Nearly the entire population of the world in Final Fantasy X is this way due to the Crapsack World setting. Sin, a whale monster that is size of a city, roams around the world and destroys everything in its path. The populace is lead to believe from the Church of Yevon that if everyone atones for their sins, then the Sin monster will go away for good. Despite people trying to do this for 1000 years, Sin still exists and you can see people trying not to crack as they keep insisting that things will be ok if they keep atoning for their sins, despite the fact that they know things have not changed for so long. You eventually find people that finally break out of their stepford smiler state and wonder if things are just hopeless.
Tidus' Idiot Hero persona is mostly just an act to deal with his angst over his Disappeared Dad. And he has a more traditional Stepford Smiler moment later on, after discovering that defeating Yu Yevon will end his own existence.
Yuna is like this too. Defeating Sin would mean her death; to add onto this, Tidus unintentionally teases her with promises of taking her to see his Zanarkand after her pilgrimage is over. Naturally, this causes her a great deal of emotional pain, and the only thing that really keeps her going is knowing that she is Spira's salvation and that she'd die a martyr. She breaks down when she learns that Yevon is corrupt, but later finds the strength to carry on and find another way.
Phone Guy from Five Nights at Freddy's is this (or as much as a character we never see can be) in all three games. He's remarkably calm for someone explaining the horrible aspects of his job to his successor. Even on Night 4, when he's attacked and killed by what sounds like all of the animatronics, he asks if you could "check inside of those suits in the back room?" and says he's "gonna try to hold out until someone checks... Maybe it won't be so bad." before giving a simple "Oh no..." The only time we hear anything resembling distress in his voice is on Night 6 of the second game, when he asks why you're at work on that day and explains that " someone used one of the suits... we had a spare in the back - a yellow one - someone used it..."
The humanoid Nobodies from Kingdom Hearts are the EmptyShell variation; their supposed emotions are an act, based on their human memories. Behind this facade, however, they're this trope. Supposedly. Really, they were effectively brainwashed into this trope by their leader Xemnas as a way of trying to separate them from their sense of self. They can feel emotion and form connections with people, and in doing so, can regain their hearts. However, Xemnas, and Xehanort's, plan requires them to remain empty shells that he can use for living Soul Jars.
Louis from Left 4 Dead is Empty. In the events of The Sacrifice comic, Louis had to kill a person who attacked him in a bathroom stall (the person became an infected or "zombie") and saw the destruction of his workplace and the city from the viral outbreak, testing his will since he always had a positive outlook in life. Louis still holds the "everything will get better" attitude, even after he and the other survivors had to endure 2-3 weeks of fighting zombies and escaping from an overzealous military force. Francis calls Louis out on this a few times, telling him that continuing to believe things will return to normal is foolish and/or insane thinking and that they are going to have to get used to striving to survive as long as they live. In the final part of the comic, Louis starts to crack when he believes there is no escape from the bridge they're on and asks his fellow survivors to kill him so the zombies won't kill him instead.
Laughing Octopus isn't the first Stepford Smiler in the Metal Gear series. Chronologically, the first would be the Sorrow, who is always shown smiling whenever the player sees him, but...
Psychonauts features both a female and male example. Crystal and Clem are two seemingly cheerful and enthusiastic campers who like to root their fellow campers on (especially Raz)... and also harbor suicidal tendencies. Most of this is Played for Laughs: "I feel so stupid for throwing myself off the roof!" "Why did you throw yourself off the roof?" "Because the poison didn't work, duh!"
A more depressing version is Milla, a perpetually cheerful party girl who hides the fact that she worked at an orphanage that burned down, killing all inside. As if that wasn't enough, she also wound up psychically hearing their screams for help as they died. Interpretations vary with the player with some seeing her as someone who's coped with the trauma in her past. Word of God says it's the latter, and that "locking up" nightmares is a perfectly healthy way of dealing with that level of trauma.
By comparison, twice in Boyd Cooper's mind, you get assaulted by nightmares and have to fight them as minibosses. So it would seem that in the metaphorical context of things, nightmares being "locked up" is more a sign that you've dealt with them and have them under control, rather than that you're suppressing them.
The backstory for the Pleasant family in The Sims 2 is scripted like this: Mary Sue and Daniel have a perfect suburban life. He's shtupping the maid, she's about to get fired, and their daughters hate each other.
This is the philosophy of several lawyers in the Ace Attorney games. It's a repeated mantra for the protagonists in Phoenix Wright: Ace Attorney – Dual Destinies, "The hardest times are when lawyers need to force their biggest smiles." They have to be optimistic and upbeat for the sake of their clients even in the face of a possible guilty verdict.