LanaLang becomes something like this around season six when she marries Lex. It actually helped build her character, which was previously little more than Clark's Satellite Love Interest.
Chloe Sullivan borders on this towards the end of season eight, after about two seasons of worse and worse Break the Cutie moments.
EastEnders has had Vanessa Gold, a lovely, only slightly tarty woman with perfect hair, a perfect name, and a perfect complexion, wearing exclusively white. She smiles an awful lot, and allows herself to put up with a cheating husband for many many years. When Max leaves her for Tanya, she goes a wee bit bonkers, including a lot of screaming, derpface and smashing living rooms, but the really powerful stuff was her obsessive cleaning when she suspected the affair.
Bree stands out as the most Stepfordish. In the pilot, her son Andrew even says that she always acts "like [she's] running for mayor of Stepford."
Julia McNamara from Nip/Tuck is half Stepford Smiler and half Defrosting Ice Queen. You have to have a little sympathy for the woman, as she has been keeping her son's paternity secret from both his natural father and assumed father. Unfortunately, her eternal struggle over "Sean or Christian?" just annoys most people.
Blair in Gossip Girl is a Type A, especially during the first season when she's with Nate. Serena accuses her of being in constant denial in order to keep her life perfect. She admits to faking her happy sparkly persona to her stepfather in Season 4: "What kind of a princess schemes and plays sex games and drapes herself in old Hollywood movies?"
Also, Nate Archibald's mother. To the point of being called the Archibot by fans.
Lemon Breeland from Hart Of Dixie is a definite Type A who also leads an entire clique of oddly similar smilers.
Betty Draper from Mad Men could be used as a textbook example; she's playing the role of '50s wife and mother so perfectly that her impending nervous breakdown seems like a surprise even to her.
It didn't help being married to Broken Ace Don Draper. The fourth season spent much time surveying the wreckage of that broken union.
Being a spunky fifties parody, the gang from Pushing Daisies has met their fair share of this trope. For example, Hillary Hundin from "Bitches", Madeline McLean from "Corpsicle" and Mrs. Vandersloop from "The Legend of Merle McQuoddy".
It's implied that Charlotte -Chuck-Charles is one of this as well. Specially when confronted with the issue of her own existence on "Bad Habits"
Daisy from Dead Like Me. She starts out as a ditzyHard-Drinking Party Girl and former actress who Really Gets Around, loves to brag about it, and acts more than happy with herself, but then her last thought is revealed: "Why has no one ever loved me?", revealing that she only acts happy with her life (and her un-life, given what the show is about). Although the Alpha Bitch and Narcissist things she also does, when viewed in conjunction with the smiling, give you sort of a clue from the beginning that something is wrong.
Quinn of Glee tries this, hoping to hide her pregnancy from her family and the rest of the school and continue to play the part of the popular, celibate cheerleader, until such point as the truth becomes too obvious to ignore. It doesn't work - and when word gets out, she loses her popularity and even gets kicked out by her parents. And according to Quinn, her mom is one of these as well (what we know of her makes it obvious she's at least a Lady Drunk).
Quinn: And you just pushed it aside, like we do every bad feeling in this house. If you don't talk about it, it doesn't exist.
Episode 12 hints that Rachel might be one of those as well (especially the Lily Allen version of "Smile"), or might become one someday (when she tells herself that "it's lonely at the top" when Finn apparently abandons her when the Glee club is due their photos for the school yearbook).
Terri tried to be one of these with her fake pregnancy.
The Bones episode "The Death of the Queen Bee", set at Bones' high school reunion, references this trope, specifically Type C. A janitor who looks extremely suspicious (played by Robert Englund, even!) is completely benign, while the actual murderer turns out to be a Stepford Smiler. To quote the janitor: "One look at her, you can tell she's off. Them smiley ones, they always give me the willies."
Amy Pond from Doctor Who shows signs of this at times, as according to Karen Gillan deep down she doesn't trust the Doctor as much as she seems to. Word of God says that in Amy's Choice the dreams were the Doctor's and Rory's and that she has no dreams of her own. Then there's the fact she has no memories of any reason to be in mourning after episode 9...
And then at the end we find out why it was just her in that big empty house for all those years....
On the Season 8 episode of Law & Order: Special Victims Unit, "Cage," Detective Beck — filling in for the undercover Benson — is looking after the sweetest little girl, who adores her caretaker. In fact, this bond is so strong, the girl sets Beck's couch on fire, in hopes that she and the detective will both die, so that they will never be separated.
V-2009: Anna is a type C and her daughter Lisa is a type C who later becomes a type A.
Effy is a combination of Types A and C. Her random personality shifts in the previous series, from Silent Bob in S1 to Magnificent Bastard in S2 to Fille Fatale and Emo Teen in S3, were all various attempts at hiding it, some more successful than others (S1 and S3 both afforded some glances Beneath the Mask). In S4, the mask finally comes off.
Cassie in Generation 1 and Mini in Generation 3 are both Type As. Cassie's mask comes off in S2; Mini's is gradually chipped away at throughout S5.
Shirley in Community displays a mild side of the trope, but she is known to have "thinly veiled rage issues" under her cheer.
Annie has moments of this as well, especially in the episode where she's planning to start a Model UN, and Other Annie steals her idea, prompting a Model UN-off to decide whose Model UN will be the official one. Annie spends the majority of the episode smiling and laughing in an unconvincing manner while clearly on the verge of a nervous breakdown.
Annie: Everyone should just have fun. But then again, what's more fun than winning? (laughs hysterically)
The fourth season premiere of Sabrina the Teenage Witch had Sabrina consider moving in with her father on her 18th birthday. Hilda and Zelda are devastated but cast a spell to give them big toothy smiles so as not to spoil Sabrina's birthday. The effect is slightly creepy.
Jill Tracy from Scrubs, especially in "My 15 Seconds", where she behaved in her typical over-the-top way despite having tried to kill herself.
Bernadette on The Big Bang Theory is a solid Type C. She always wears the same smile, even when saying some incredibly creepy and threatening things (such as crossing Ebola with the common cold, or advising Howard on how to talk to her father).
24: This trope also reveals itself very early on with David Palmer's wife, Sherry...aka the eventual First Lady. At first she appears to be a generic, stereotypical "politician's wife", dressed in pink, dowdy outfits and pearls and posing for awkward photo ops. Then over the course of the day it's hinted that beneath this facade she's quite savvy at political hardball herself and is willing to step on a few toes to help her husband win. OK, nothing too bad just yet. But then it gradually becomes clear that she's been involved in some very unsavory dealings in the past and that she still is. And once her husband discovers this (even he didn't know just how bare-knuckled she actually was), she drops all pretenses (at least in front of him) and basically reveals herself to be a cold, cynical and downright nasty Lady Macbeth type figure. And she's freaking scary. At one point, she even tries to convince an intern to sleep with her husband because she's hoping to use her to spy on him. It gets especially creepy when we see her doing these unsavory things and spouting borderline psychotic dialogue while dolled up in the most cutesy, matron-like outfits ever, further underlining just how much of a Type C Stepford Smiler she really is. Also, anyone who finds out about her true personality—including her husband the President—becomes utterly terrified of her. At one point she actually kills a guy by TALKING TO HIM.
Regina from Once Upon a Time is something of both a Type A (or least a Psychotic Smirk) and Type C. While most of the characters (once the curse breaks anyway) recognize her as Type A, only Arch-Enemy Snow White and possibly Jimmie Cricket recognize her as a Type C. Snow White even comments at one point that she is a deeply brokenwoman.
In an episode of Charmed, Leo casts a spell on Piper turning her "psychotically chipper" as Paige puts it.
Phoebe becomes this (and also black-and-white) because of Grandma's enchanted (by HER) wedding ring.
In Girls, Marnie projects this trope when talking to her ex Charlie.
Audrey: Omg, are you one of those real housewives?
It depends on how you look at it but Valery Denton from The League of Gentlemen has to put up with a lot; a husband who is obsessed with toads and keeping the house clean, a pair of Creepy Twins who constantly appear at your side out of nowhere, and a hidden desire to have had a son ( one of the reasons for why she wants to keep Benjamin in their house) all the while smiling and not complaining.
Game of Thrones: Ser Loras Tyrell is a Type A in Season 3. He puts on a charming smile and a pleasant disposition most of the time, but his mask slips at a very public event in "Second Sons", and his misery betrays itself more subtly in "Valar Dohaeris" (Loras—who is no longer paying attention to the dinner conversation—has a melancholic expression when King Joffrey says, "I'm sure she knows what she's doing"). In "The Climb", he sadly tells Sansa Stark, "It's [King's Landing] terrible isn't it? The most terrible place there is," which clearly indicates that Loras is suffering in silence.
The android Ted from Buffy the Vampire Slayer was obsessed with reliving his creator's idea of a 1950s dream marriage, albeit with the aid of narcotics. (Though an android, he's chauvinistic enough to qualify.)
Spike himself also falls within this stereotype; despite all of his posturing as far as being a murderous bad-ass vampire, with the body-count to back up his swaggering, the dude is still the horribly insecure, Momma's Boynerd who writes crappy poetry, who overcompensates for his nerdiness by acting like a big time vampire. This was most notably shown in his origin episode, which contrasted Spike's boastful tales of past exploits with flashbacks that reveal how lame he used to be, right down to revealing that his nickname "William the Bloody" originally referred to his "bloody awful poetry."
He's both. The above would have him be something of a...Stepford Snarker, but over the course of his Character Development and becoming a woobie he's also still an asshole. With codependency problems. He and Dru were groundbreaking for the series when introduced because they were very clearly people in addition to being monsters; Spike's whole character arc explores this. And messes with him for fun, apparently.
Supernatural: If you know what's going to happen, Dean comes off as a version of this trope in the supposed lighter moments of Seasons Two (the season where everything leads up to him making the demonic pact) and Three (when he has done so). Whether it's the Daddy Issues or Survivor Guilt or his impending death/suicide, he loves to pretend that everything is perfect when it's really, really not.
Another codependent one.
Played with, Season 7's episode 11 gives us this advice:
Frank (to Dean): “Here’s my advice you didn’t ask for: Quit. You want to keep going? You’re going to drive yourself into the ground first. Do what I did when I was 26 and I came home to find my wife and two kids gutted on the floor. Decide to be fine ‘til the end of the week. Make yourself smile because you’re alive and that’s your job. Then do it again the next week. I call it being professional. Do it right, with a smile, or don’t do it."
Which leads us to the ending of the episode where Dean, as he's driving, tries to smile and utterly fails.
Sherlock's Jim Moriarty is Type C all over. He's got a lilting Irish accent, grins and giggles a lot, and then does a 180 and threatens to turn you into shoes...and then smiles.
Dexter. On the surface, Dexter Morgan affects a harmless, chipper personality to fit into society and hide the fact that he is a sociopathic serial killer. And empty. Over the course of the series, however, he becomes more in touch with his feelings and enjoys periods of legitimate happiness.
Watching Dexter's face for real versus feigned expressions is very interesting, especially since the face you're watching actually belongs to an actor who doesn't mean the real ones or the fake ones.
Nobori Taiga from Kamen Rider Kiva: Friendly, polite and nice to his old friends, but secretly working to destroy humankind.
Eiji Hino from Kamen Rider OOO is one of the Type B Empty kind. He is cheerful and always ready to help others, without showing any desire for himself. Other characters even explicitly call him empty. The fact he is devoid of any desire for himself is actually a major plotpoint, as this makes him the perfect host for the Purple Core Medals, which slowly turns him into a Greeed.
Pretty much every male cast member of The Shield fits this description. But most notably, there are Curtis "Lem" Lemansky (popular police officer and all around good guy who has ZERO self-esteem and basically serves as a doormat for his "best friends" on the Strike Team, leading to crippling ulcers, a mini-nervous breakdown, committing criminal acts that ultimately lead to his arrest, death, and ultimately denounced as a monster), Shane Vendrell (who loves his family to the extent that he murdered his best friend/partner rather than risk having him turn state's evidence against them, but basically murders his pregnant wife and toddler son rather than risk having Vic Mackey reveal to his children the sins committed by his father), Police Captain turned City Councilman and Mayoral Hopeful David Acaveda (affable but somewhat slimy boss who is into rough sex, arranged the murder of a man who raped him, strained relationship with his wife after being told by her that she would have preferred him being killed to him being raped, willingness to work with the Mexican Mafia and use their blackmail files of prominent people to further his career), Ronnie Gardocki (lovable nerd whose darkness manifests itself in full force in season seven, by way of the lengths he was willing to go to see Shane Vendrell murdered as payback for Shane killing Detective Lemansky), and John Kavanaugh (brilliant and decorated Internal Affairs police officer whose devotion to law and order hides the fact that he cruelly divorced his mentally unstable wife the moment she became an annoyance to him).
Not to mention Vic Mackey, whose stepford smile hides a monster that all others pale in comparison to. So it says something that in the end, Vic loses EVERYTHING in the finale including his "good" name but ends up in the final scene of the series, putting on a stepford smile and walking into the darkness, as far as not letting his karmic final fate as a glorified temp desk worker with the Feds slow him down.
Spoofed somewhat in season six of 24; after the father of one of Jack's unlucky girlfriends lampshades in graphic detail how bad things always befall Jack's loved ones, to the point of outright telling Jack that he's cursed and that he would never never be allowed near his daughter again as a result, Jack spends the last moments of the season breaking into the father's house and holding a gun on him, while ranting incoherently about how he's not cursed and ordering the guy to take back what he said.
On CSI: NY Flack became one in season 6 of the show after his girlfriend was killed in the season 5 finale. Characters eventually started to guess something was seriously wrong, however, because he didn't keep the mask completely on all the time. Eventually, Mac saw through it and tried helping him, but Flack pushed him away. Eventually ended with Flack having a brief Heroic BSOD, finally letting Mac in, and eventually pulling out of it with help from Mac and the others.
The Doctor, most noticeably in his Ninth, Tenth, and Eleventh incarnations. The Tenth Doctor acts bubbly and cheerful, cracks jokes in dangerous situations, and always smiles despite the odds. Underneath the optimism, however, he's frequently revealed to be suffering from various levels of acute mental instability. Ten did seem to be pretty genuinely happy up until he lost Rose. It all pretty much went downhill after that.
And culminated in The Waters of Mars in which his Stepford Smiler status is taken to terrifying new heights as he calmly and cheerfully explains to the captain of a destroyed interplanetary base that the lives of all her crewmembers are utterly unimportant to the universe, and that he'd only saved her life to prove a point. The woman is so disgusted by his attitude that she shoots herself, thereby saving the timeline of the entire human race. Which she wouldn't have done if he hadn't explained how important she really was back when he was leaving her to die.
Eleven is usually energetic, cheerful, and Adorkable as all hell. He also immediately recognizes that a villain is a part of his own subconscious because "there's only one person who hates me as much as you do", and, when presented with the (false) opportunity to find more Time Lords, was more eager about the chance to beg for their forgiveness than for companionship or a chance at locating friends.
Then there's the scene when he's offered options for the TARDIS' voice interface. Himself? "Nonono, give me someone I like." Rose Tyler? "Oh, great. Give me guilt." Martha Jones? "Also guilt!" Donna Noble? "More guilt!" Finally, he says "There must be someone left in the universe I haven't screwed up yet!". Current companion Amy? Yeah, he thinks he's effing up her life too.
Matt Smith actually described Eleven as a person who had to act happy and cheerful and put on a silly hat, otherwise he'd hang himself.
Nine: When his lone season started, he appeared to be manic and upbeat with a bit of rudeness mixed in and a small dark streak. Slowly, as more and more information about the Time War is revealed, it's shown that he is plagued by Survivor Guilt and searing self-hatred. This culminates in "Dalek", when he comes off as a Type C during his terrifying verbal assault on the imprisoned creature. He gets better, though.
The Master in his John Simm incarnation certainly counts as well. He manages to get himself elected Prime Minister of Britain, despite being both a homicidal sociopath AND a time-travelling alien. He's also disturbingly cheerful when discussing the fiery destruction of his home planet and all its inhabitants. He later spends an entire two-part episode trying (and succeeding, mostly) to bring them all back.
Star Trek: Deep Space Nine: Garak is both a Stepford Smiler and a Stepford Snarker. He's always amiable, cheerful, engaging and polite... and also very sarcastic. Midway through series 2, he suffers a life-threatening breakdown that reveals he's utterly desolate by his status, is living under torturous conditions (human norms make the station too bright and cold for a Cardassian) and can barely cope with how much the Bajorans on the station loathe him for being a Cardassian. After Bashir helps him recover, he returns to his amiable, cheerful, snarky disposition, but every so often episodes do dive Beneath the Mask to show the audience that his exile remains a source of great pain and loneliness for him.
The eponymous Merlin seems to be The Pollyanna (albeit a very dark version), but he has his moments of this. Like this particular Tearjerker from 2x08.
Arthur: It has once again become clear to me that those who practice magic are evil and dangerous, and that is thanks to you.
Merlin: (smiles with the saddest eyes you've ever seen) Glad I could help.
''Person of Interest: Elias smiles pretty much constantly in every scene he's in, that and the fact that he's a Magnificent Bastard makes it difficult to predict whether he's going to double cross whoever it is he's talking to or not.
Blaine from Glee is a type A when we first meet him in the second season. He puts on a Big Man on Campus facade to impress Kurt and his friends in the Warblers, but it's a mask for his insecurities and his being haunted by his decision to transfer out of his old school instead of standing up to his bullies. He gets over it once he starts dating Kurt and transfers to McKinley, however.
30 Rock: Kenneth Parcell has shades of Type 1. More or less confirmed in one episode when he flat-out admits to Jack Donaghy that he has to lie to himself in order to get through the day without cracking.
"Every morning, I look in the mirror and say 'it's gonna be ooookay,' but it's not. And I don't know how much longer I can take it... Have a swell day, sir!"
In Mr Selfridge, Harry Selfridge is a major example. He's always chipper around his family and staff, but he's also under a lot of pressure, and his marriage is falling apart. A number of scenes show him entering a room scowling, only to realize that he's being observed and instantly shift into a big smile.
Mixed Gender Examples
Gem and Gemma of Power Rangers RPM. The disturbingly cheerful smile never leaves their faces, whether they're talking about explosives, military strategy, their time imprisoned by the enemy and forced to do hard labor in an enemy factory producing Mooks...
They also love drawings of unicorns, butterflies, and rainbows, and work them into anything they write or draw (including a very, very confusing map to said factory, composed entirely of unicorns and rainbows).
Another TZ example would be "Number Twelve Looks Just Like You", where Stepfordization is a standard part of becoming one of the beautiful people.
Similar to the "It's a Good Life" example, the Monty Python "Fairy Tale" sketch had the citizens of Happy Valley who were always happy and cheerful, because to be otherwise was a crime punishable by death.
Another example from Dexter; the Trinity Killer and his family. The family act like a perfectly happy, wholesome family while hiding the severe physical and psychological abuse they suffer. Trinity acts like a good man and pillar of the community while hiding that he is a brutal serial killer.
Comedy example from Father Ted: the O'Learys, who behave like a perfect, arm-in-arm couple while anyone else is around, but spend the rest of the time hurling obscene abuse at and trying to brutally injure each other.
On an episode of Roseanne, David got a job at a theme park where all the employees (and soon David himself) are turned into Stepford Smilers. The Conners are thoroughly creeped out.
On Boardwalk Empire, Stepford Smiling is a way of life for New York gangsters Arnold Rothstein and Meyer Lansky. Rothstein smiles constantly - when he's amused, he smiles. When he's confused, he smiles. When he's irritated, he smiles. Even when he's chewing someone out over the phone, he smiles. You know the shit's hit the fan when Rothstein chews you out without smiling. Lansky picked up the smiling habit from his boss, though his are less unpleasant and more "can't we all just get along and make money"?
Among the ladies, the undisputed Queen of this trope is Gillian Darmody. She always smiles and acts cheerful to everyone to survive and get what she wants. She remains the concubine of the man who raped her as a child until she momentarily drops the act to enact her revenge. Even afterwards, she pretends that they're still good friends. In all other aspects of her life, she behaves as the smiling hostess even when she's talking gritty business and being outright threatening.
To call them "smilers" is a gross understatement. They're more like... stepford newlyweds-who-just-found-$500-in-the-house.
Most characters in Twin Peaks live this trope - it is one of the key fascinations of David Lynch and common in his work. The key theme of Twin Peaks is taking a dreamy, perfect small rural town with white picket fences and exposing the hypocrisy, instability and literal evil that underlies it everywhere. Shades of grey abound.
The Rick Mercer Report invokes this in thisParody Commercial about Canada's Liberal Party. Though the particular parody ad involves a male character, it's used as a metaphor for issues applying both to male and female members of said party.
30 Rock has the Jessup family who takes this so far that their family crest is a knight refusing to talk about his feelings.
Doctor Who has the Ood, as revealed in "Planet of the Ood". They appear to be happy and servile but are really sad shells of their former selves, having lost both their second brain and their psychic link to the group brain. In stories with the Ood set after "Planet", the slave Ood are partially restored, reconnected to the group brain, while the non-enslaved Ood have everything back.