A Beautiful Mind: The main character is a genius whose mind is the most important possession has. He goes crazy... His wife see him succumb to his own inner demons against which she is powerless to help him.
A Clockwork Orange: The "Singing in the Rain" scene is designed to send chills down the spine of any adult. The themes of absolute evil and of a manipulative government attempting to rob people of free will and using the cover of mental health to silence dissidents are pretty chilling on a more subtle level as well, and were surely even more so during the Cold War era in which the film (and novel) were made.
Aunt May stays up night after night, waiting for her nephew, who is possibly the last of her family, to come home from his nighttime activities (and left wondering what kind of activities they are), always with bruises and claw marks.
Peter invokes Adult Fear when he convinces Captain Stacy to let him leave after being captured the police. He tells him that his daughter Gwen is alone in Oscorp Tower and the Lizard is on his way there.
An American Crime is the worst fear of every parent who has had to leave their child with another person, especially if that person is just an acquaintance. It really doesn't help that the story really happened.
Batman Returns: The Penguin is made on this. His masterplan consists of taking Gotham's children into the sewers and killing them. He gleefully gloats about it, claiming that it's the parents' fault for having left them unprotected at home in order to attend to Max Schrek's ball.
Ten guys are waiting for The Hero to be at his most vulnerable (alone in a public bathroom) to beat him up. NO ONE would have noticed it either as it was happening.
Cloud's great grandmother was raped by three men when she was picking flowers for her wedding.
Mr. Tipping's methods for helping speed up a housing application apparently involve molesting young women.
The Blob: In the 1988 remake, the cheerleader Meg Penny learns from her parents that her brother Kevin and his friend are missing while the town is under quarantine, thinking they snuck out to see a slasher movie. What makes this terrifying was the fact that Meg's little brother is now in danger of being eaten by the titular monster now getting bigger by eating anyone that gets too close. She arrives to find the theatre is in a state of panic with Kevin and his friend desperately trying to use the emergency exit and while she does save them, they wind up having to evade the Blob in the sewer. The Blob follows them down there and Kevin's friend then gets pulled underwater. Meg tries to save him only to later see him rise up from the water half-eaten; imagine dying by drowning and being eaten/dissolved alive at the same time. What makes this all the more horrifying was the fact Kevin's friend has an older brother that let them both into the movie and we saw his mother hoping he was going to come home safe. At least Meg and her brother survived...The guilt the kid's older brother is going to feel for the rest of his life knowing that his little brother would still be alive if he hadn't helped him sneak into the movie.
Bubba Ho Tep: growing old and weak and finding yourself left to die in a care home, with your children "too busy" to come and see you.
Changeling is all about a woman leaving for work, coming home to find that her child is gone, and then receiving no help at all from the authorities about it. And then comes Act 2, and we find out that there's been a serial killer kidnapping children, and that Christine's son isn't the first cover-up the police have done. Also, her son is never found.
The Changeling, a 1980 horror film starring George C Scott, has the protagonist lose his wife and only child in an accident. The rest of the film, he is haunted by the the ghost of another child who was brutally murdered by his father for his money. Infant mortality seems like a recurring theme in his life.
Danika is the story of a genuinely desperate housewife, whose main fear is to lose one of her children or the three of them. This obsession of overprotecting her kids, turns out to be the result of a traumatic childhood experience, in which poor little Danika loses her brother in a road accident.
Batman Begins shows the obvious example of Bruce seeing his parents die, but also includes seeing your home burned to the ground, what it is like to live in a fairly realistic city so filled with crime that even the police belong to the mob and murder is a common occurence and what it is like to be betrayed by a Parental Substitute that helped you overcome your flaws twice, actually.
The Dark Knight: Two-Face and the Joker were frightening enough on their own, but the part that was also creepy was the fact that, even after faking his own death, Commissioner Gordon still can't protect his own children—and Mrs. Gordon's response to the ploy!.
Aside from the business of a child having to grow up in a Hellhole Prison and Gotham City being held hostage and thrown into anarchy, The Dark Knight Rises also deals with the topic of a loved one turning out to be a Bitch in Sheep's Clothing and plotting against you the entire time. To be more specific, Miranda Tate is revealed to be the actual Big Bad Talia al Ghul, who proceeds to backstab Bruce in more ways than one.
A major metropolis is seized by a terrorist organization and held hostage for five months. The poor citizens are forced to eke it out, with the very possibility of being gunned down by terrorist goons at any minute. The police are trapped udnerground, cut off from the citizens that need their protection, and outside intervention, especially by military forces, and leaving the area is impossible due to the terrorist leader threatening to blow up the entire city if any of those things happen. Oh, and some of the people trapped? They were fans of a visiting football team, forced away from their loved ones with no way to contact them and inform them that they're at least alive.
In the first three films in the Die Hard franchise, this is the drive behind most of our hero's actions. The first film sees our hero getting caught in the middle of a terrorist take-over of a high-rise building, with no way out, holding dozens of hostages with his wife among them and the police offers arriving to save the day being no help at all. The second is much of the same, except with entire plane-loads of people coming in for the holidays. The third film has a major subplot about a terrorist bomb in an elementary school.
The Duchess: Your husband can take your children away from you, and there's nothing you can do about it because you're a woman and he has law on his side. The same fear is brought about by Iron Jawed Angels.
Also Dear Zachary. Your children could be taken away from you and given to their abuser by the court, which finds it OK because she's their mother.
Also, in Seduction in a Small Town: some Manipulative Bitch can perfectly convince others that both you and your husband are horrible child abusers and not only have your kids taken away, but send you guys to jail for that. Twice.
Chinatown: Got evidence of corruption in the government? The rich and powerful will just cover it up. Not fair? Too bad; you're a nobody.
Elysium: Frey's daughter is dying of cancer, and there's nothing she can do to save her.
Eraserhead: If giving birth to a creature so horrible that no sentient being would want to touch it with a 10-foot pole isn't every soon-to-be parent's worst nightmare, then the fact that it makes your spouse leave you and force you to raise it by yourself certainly is. Loathing one's own baby to the point that stabbing it through the lung (if you can even define it as a "lung") with scissors becomes a viable option is something no adult wishes to experience. Oh, and the fact that everything else in this movie is filled to the brim with the regular kinds of fears doesn't exactly help.
Eye For An Eye: This 1996 drama starts with Karen McCann talking with her home alone teenage daughter over the phone when the slime bucket Robert Doob breaks into the house and all Karen can do is listen as Doob (non-graphically) rapes her daughter before killing her. Oh yeah, and a minor technicalityprevents him from being prosecuted and thus punished for what he's done.
Fatal Attraction: Alex kidnapping ex-fling Dan's daughter Ellen. It's not just every parent's worst nightmare, but all the elements surrounding it—that your child could go off with a stranger just because he/she seemed nice, that other adults who should have protected your child would instead let them go, that someone could have been watching and stalking your child, just waiting for the right moment to snatch them. Though Ellen is returned safely, the cold hard fact is that Alex could have harmed her if she wanted to. Dan's demeanor in the police station afterwards demonstrates how really and truly terrified he now is.
And it's not just him acting alone but a congregation of his followers. A priest drowns a baby at baptism. A nurse murders the infants under her care. Even a couple of children deliberately throw a ball so that it pushes a stroller into the path of traffic.
The Hand That Rocks the Cradle: How about unwittingly hiring a Nanny that is bent on taking revenge on you for inadvertently causing her sleazebag husband's suicide and subsequent miscarriage as a result of the stress it brounght on.
One of the nanny's methods for taking said revenge involves breastfeeding the baby!
The thought that your doctor, someone you're supposed to be able to have the utmost trust in, could instead take advantage of that trust and assault you. Though Claire and other women come forward, leading to the doctor's downfall, this happens far too often in Real Life—often with no one coming forward, thus enabling these perverts to continue their behavior.
In The Hobbit, Bard the Bowman's greatest fear is that he can't protect his three children and Laketown from the dragon that resides within the Lonely Mountain. This is the main reason why he discourages Thorin and Company from reclaiming Erebor. In the end, Bard's fears turn out to be prophetic when Smaug leaves the mountain in a Roaring Rampage of Revenge and sets his sights on the defenseless citizens of Laketown.
Discussed in Home Alone, where Kevin talks with Mr. Marley about how being an adult doesn't mean that you're not afraid of anything.
And of course that what kind of parent do you have to be to leave one of your children behind when going on vacation. Not just once but multiple times.
In Homeward Bound: The Incredible Journey, the pets encounter a scared, crying, little girl who is lost in the woods. Later, we see her parents searching for her. In the sequel, a woman screams as she watches her house burn, knowing her son is inside. Shadow saves him, but it's a close thing.
In Hook not only does Captain Hook kidnap Peter's children and threaten to do the same to his descendants, he tries to brainwash them into loving him instead. It almost works with Jack (who was already distressed), but utterly fails with Maggie.
It's not much better when he kills a 15-year-old boy, Rufio, in front of Peter and all of the new Lost Boys.
In the beginning of the film, Peter, his wife and Wendy returned home after a dinner to find that their home was broken in and desperately searched their children's empty rooms before realizing they were kidnapped.
Inception. The protagonist is forced to flee his home and his country, leaving his very young children behind, possibly forever. There's also the horrific situation when he has to watch his beloved spouse succumb to mental illness and suicide - and realize it was his mistake and that he was responsible.
In Jack the Giant Slayer, King Brahmwell fears for his daughter's life, but is forced to have the beanstalk cut down before she can make it down safely, to prevent the giants from climbing down to Earth. When Jack saves her life and reunites her with her father, Brahmwell is visibly relieved. What he says to Jack as he gives him a bag of gold for his efforts shows how much his daughter means to him:
"As a king, I can offer much in reward. As a father, I can never reward you enough."
Jurassic Park has the scene where the two kids, Lex and Tim, are trapped under the windshield of the park jeep with the T-Rex trying to break it to get to them and kill them. For a little while, there's nothing the adults can do, and the kids are screaming at the top of their lungs the whole time. This troper's mother still has not finished the movie because she can't watch that scene.
Kill Bill: The scene in which the Bride fights Vernita Green and Vernita's little daughter Nikki steps in perfectly shows the terror that a mother can feel when she realizes that not only has her Dark and Troubled Pasthas caught up with her, but that her child is about to be utterly traumatised.
The Bride was pregnant on her wedding day. When she wakes up, she's not pregnant any more, and she has no idea what happened to her child.
The French film L'Argent de Poche gives us a comedic, though not tasteless example when the mother of the infant Grégory leaves him alone in the apartment on one of the higher floor with the windows open while she searches for her wallet. Grégory inevitably ends up hanging from the sill above a crowd of terrified onlookers before falling and landing in a hedge, unharmed. Suffice to say, the mother, upon seeing her child in the hedge, promptly passes out. As this film is more or less a social commentary about the world children inhabit that adults often fail to see, the Adult Fear is played completely straight.
Law Abiding Citizen. Having your home being invaded is bad, and crippling you is worse, but the ultimate nightmare is when he rapes and murders your wife and daughter in front of you. Then, a killer gets off with a light sentence just to make sure that the justice department can get the other guy.
Little Sweetheart: The protagonist's daughter has been associating with strangers, who turn out to be criminals. Now she's missing, her clothing is on the beach and a gun is wrapped in it. That's for Elizabeth. For Thelma, you have the fear that your child will become a criminal, and at age 9, Thelma is easily an Enfante Terrible.
The beginning of Return of the King has Sméagol kill Déagol over the Ring. Well, what if the friend you trusted most easily turned on you over one little trinket?
In Two Towers, Théoden buried his son after being under a spell from Saruman for a long time and was so trapped by the spell that he wasn't aware about his son dying until afterwards. And to top it off, Théoden had also banished his nephew and was completely unaware of his beloved niece being sexually harassed by the same advisor who was manipulating his mind.
Théoden: No parent should have to bury their child.
Although the hobbits aren't children, their small size and innocence invoke feelings of protect similar to children, and the members of the Fellowship clearly think of them as their charges. Boromir's anguished "They took the little ones!" as he is dying is particularly heartbreaking.
M: Mrs. Beckmann's increasingly desperate cries as she calls for her daughter, who was kidnapped and murdered while walking home from school, is enough to strike terror into the heart of any parent. And that's just how the film starts.
Mean Girls: Regina's mother watches her daughter get hit by a school bus.
The film gives us the three precogs, who spend all of their time being heavily sedated and floating in a pool, getting endless future visions of murders. And then we find out that the precogs were all just the children of drug addicts, taken from their families. Oh, and there used to be more, but all but those three died. And then we find out that when one of the mothers kicked her drug habit and demanded her daughter back, she was murdered because the precog system couldn't work without her. The entire plot is driven by Agatha's desire for her mother's death to be avenged.
Our protagonist, Anderton grieves the loss of his son. When we get to see how it happens, it's horrifying. They are at a public pool, playing a game of who can hold their breath the longest. Anderton dives under the surface and more and more notices how something is off. He gets up, sees his sons cyclops floating in the water and gets up screaming his name, but he is nowhere to be found. The scary part is that the pool and area around is full of people, who all must have seen it, but not noticing. Part of the premise is that Anderton is himself implicated as an upcoming murderer, whose victim is someone he's never yet heard of. Anderton tracks him down to prove his own innocence, and walks into a Room Full of Crazy. Upon seeing photos of his dead son among piles of others, Anderton quietly accepts that he is going to kill the man after all. Made worse because it's an obvious frame-up.
Anderton's intended victim willingly agrees to be murdered and poses as a child molester and killer. He did it for unexplained reasons, implied to be trying to provide for his family through allowing his own death at Anderton's hands — a whole other kind of Adult Fear.
It has one utterly chilling scene for adults, when Sean's father sees Dracula and realizes the supernatural things his son has been so scared of all day are real. And then Dracula tells him "I will have your son" before turning into a bat and leaving.
The very premise of A Nightmare on Elm Street is a nightmare to any parent — the possibility of your own child being horribly assaulted and murdered by a psychopath in a manner that you have absolutely no way of protecting them from. And worse, this psychopath is supposed to be dead, because you and other parents took the law into your own hands after his string of child murders went unpunished due to a technicality.
Wes Craven's New Nightmare may even have more adult fear to it than the other entries, as a major focus is Heather trying to protect her son Dylan, who is significantly younger than Freddy's usual teenage victims.
The Canadian film Obsessed/Hitting Home has two examples of this going on. The first involves a single mother losing her only child in a bloody hit an run. The second involves that single mother menacing the children of the driver responsible for the hit and run - including kidnapping his young son.
The first non-action film by Jet LiOcean Heaven is half Adult Fear and half Tearjerker. It concerns dying and living your offspring defenseless in an uncaring world. Not only that, what happens if your child is autistic to boot? The thought was so scary that Jet Li's character thought of mercy killing his own child in a double suicide. How scared would a person be if he decided doing that to his own child?
Orphan: having your children in danger, your spouse turn against you, and being thought insane when in reality you are the only one who knows what is really happening. Then the terror of having it be even worse than you already thought.
The premise for El Orfanato (The Orphanage) went along the lines of "You remember Peter Pan and Never Never Land? How it was such fun for the kids? Now think of how their parents had to feel in that situation!"
A ten-year-old girl got lost in an unfamiliar, deserted city lying in ruins, her parents are probably dead and then she's chased by a Giant Enemy Crab who wants to eat you because its masters genetically programmed it to hunt down and kill every last human it can find.
Raleigh witnessed his brother's death from inside his brother's head and was completely helpless to stop or do anything about it.
Herc's reaction as he says goodbye to Chuck and when he listens to Chuck's last words before his Heroic Sacrifice because he should have been there fighting right next to his son but due to circumstances, he wasn't. Outliving your child is every parent's worst nightmare.
Another Guillermo Del Toro film: Pan's Labyrinth. The Fair Folk? They're creepy as hell, but the darkest and most horrific scenes of the film are based not on the ancient magical beings, but on the very real evils of fascism, the sociopathic monsters the ideology attracts, and the atrocities these people commit in it's name.
Paranormal Activity 2: An invisible supernatural force is trying to kidnap your one-year-old son because one of your ancestors made a pact with a demon. An in the end, it succeeds.
Discussed in Parenthood. Kevin suffers severe anxiety issues as a gradeschooler, in part, because he "was first" and his parents frantically over-protected him as a child.
Patriot Games: Ryan saves the Royal Family from being killed in a terrorist attack, and now, one of the terrorists wants revenge on Ryan for killing his brother. He has broken out of prison with the help of his comrades, and will stop at nothing until Ryan and his family are dead.
Cathy: It was him, wasn't it? He's never gonna leave us alone.
Pirates of the Caribbean: In the first film, a toddler is shown wandering alone, screaming for his mother during the ransacking of Port Royale. He's just barely saved by a passing woman before being crushed by a burning building. Thinking of one's own child alone, terrified, and screaming for you during a disaster can certainly send a stab of fear through any parent.
Poltergeist: In the new home the Freelings have recently moved into, both of their young children are attacked by supernatural forces, with the daughter being taken from them by spirits. They can communicate with her over television static, but there's absolutely nothing they can personally do to bring her back to safety amid her terrified screams.
Prisoners: The two families experience this when both of their young daughters are kidnapped.
The Purge: The Sandin parents have a lot to be worried about, because they're trying to set a good example for their kids by doing nothing bad during The Purge. That doesn't even touch on the fact that one of their kids lets in a stranger because he looked like he needed help or that a psychopathic gang is quite willing to launch a home invasion and kill everyone in it....
The Pursuit of Happyness depicts a father trying really, really hard to provide for his kid, and failing. There's no zombie apocalypse, no external mustache-twirling villain, just the inexorable facts of the matter and a string of bad luck. He ends up with his son in a subway-station closet, hiding from the elements and hoping they'll be able to stay there overnight. If you've ever been responsible for providing for another human being, this is terrifying.
Red Dawn's entire concept is built around this, especially for Americans whom the idea of being invaded by a foreign power seems distant. Summary executions of family members, neighbors turning into The Quisling for the occupation forces, being forced into fighting against an overwhelmingly powerful hostile military by hiding out in the woods, hunted like animals.
In The Ring, the protagonist is fairly collected at first in the face of imminent death. It's the imminent death of her son that panics her, and ultimately drives her to desperate measures. This theme is inverted in the Japanese sequel Rasen: Andou has already lost his son, and he ends up making an extreme moral compromise because Sadako can bring him back.
Sarah's Key: You are being persecuted by your own Nazi-friendly government, your husband has been arrested, and the police has come to arrest you and your kids too. Your daughter locks her younger brother in the closet to protect him, and you are rounded up and deported after a few days. Then you get separated from your daughter and taken to Auschwitz, and all the while you know that your young son is still locked up and likely starving in the empty house.
The Shining: A supernatural force exploits your previous vices and drives you to murder your beloved wife and son. This is scary enough, but it goes deeper: to what extent would this have happened anyway? The supernatural forces may have given it a kick-start, but the darkness was already present. The fear becomes the more realistic fear of being unable to overcome one's own secret darkness.
Star Wars: Anakin falls to the Dark Side because of the fear of losing Padmé after already witnessing his mother die.
Sophie's Choice. Having to choose which of your children to send to an inevitable death.
Early in the film, a father in London will do anything to save his child from a terminal illness. Even suicide-bomb a Starfleet records office when John Harrison offers to save his daughter in exchange.
It has the death of Pike and is in obvious pain and fear. Spock tries to comfort the former in their final moments but fails.
Kirk's death.Spock could only helplessly watch and do nothing to save or comfort his best friend.
Stoker runs on some standard middle-tier adult and coming-of-age fears: losing a spouse or a parent in a car accident and finding out that they were keeping things from you, realizing you're getting older and being afraid no man will ever love you again, realizing you're getting older and you're not a kid any more, worrying your child might prefer their other parent to you and that it's too late to win their love again, seeing a parent descend into depression and alcoholism, anxieties about what family means and what it means to have a house to come home to. But what takes the cake is something completely horrifying. The plot hinges on the death of a four-year-old boy by being buried alive while playing, by an only slightly older sibling. Jonathan's toys and the decorations for the sandcastle he was making are strewn around him, and the perpetrator lies there numbly, unbothered. The kid responsible is taken away to be institutionalized, noncomprehending, but becoming frightened and resistant when he's pulled out of the back seat of the car. This is juxtaposed with the same child, now an adult man, sitting in the front seat of a car terrified and furious that he's going to be abandoned again while his big brother is faced with the impossible choice of forgiving his clearly disturbed little brother for what he did (on purpose? on accident?) and for the way it tore the family apart, or keeping him far, far away from his own wife and child.
The Superman films have plenty of this, but the Darker and Edgier reboot Man of Steel thrives on it. There is the fact that sending Kal-El away from a dying Krypton is never an easy thing to watch; but the film takes it further by playing up the elements of Clark being an outcast because of his background, bullied by many and his loved ones often not knowing what to do. There's the whole scene where the bus crashes into the river and Clark has to make a critical decision whether or not to let his classmates die or risk exposing his secret. There's Jonathan Kent not knowing how society will react to Clark once he comes of age and ultimately sacrifices himself to protect his secrets. There's General Zod being depicted as an unrepentant mass murderer. There's the element of Clark being a drifter and having to keep a low profile through most of the movie. Once Clark finally becomes Superman, he has to deal with the US government deciding whether to risk trusting an alien from the same planet as Zod to stop him; and the rest of the film's highly realistic treatment of alien warlords causing destruction in a major city. The film even has Superman ultimately having to kill Zod to prevent any further harm towards humanity; and Superman's reaction when he does so clearly says he did not want it to come to this.
Taken features this as a driving point in the plot, where two teenaged girls are kidnapped and sold into an underground prostitution ring. Unfortunately for the criminals, the father of one of these girls is an ex-CIA Papa Wolf, who has a very special set of skills. Though he manages to rescue only one of them, his daughter. Her best friend dies.
For all the city-destruction and visible skeletons in Transformers: Dark Of The Moon, the scariest bit comes when Laserbeak transforms into a pink, kid-sized version of Bumblebee to trick a little girl into letting him in so that he can kill her father. Up to that point, Laserbeak had been an extremely efficient killer, able to hide as a number of innocuous objects, but that's pure psychological torture, and if he let the girl live. Her guilt must have been immense...
In Revenge of the Fallen, Sam's parents are kidnapped by the Decepticons in order to lure him into a trap. Once Sam and Bumblebee have foiled the trap and freed his parents, his dad takes charge and declares that they need to stay together and escape. Only for Sam to insist that he has to go back to the fight and do what needs to be done. And then his parents later watch helplessly as Sam is killed by Megatron. Even though Sam gets better, his father's cries of That's my son! when the soldiers push him back so the Medic can do his work are heartbreaking.
In Unbreakable, there is a scene where the protagonist's son steals his gun and tries to get his father to admit to being invincible, by threatening to shoot him. It is genuinely terrifying to watch him try to talk his son down from doing it.
The Untouchables opens up with a couple of Al Capone's bootleggers trying to persuade a guy to sell their booze at his store. He refuses because it's terrible booze. They seem to accept his answer and "accidentally" drop a bag when they leave the store. A little girl who was in the store at the time picks it up and tries to return it to them. Said bag is a bomb which promptly explodes. Later in the movie, the mother of the dead girl visits Elliot Ness and reassures him that he is doing the right thing in opposing people like her daughter's killers.
Where The Heart Is has Ashley Judd as a single mom who comes early home from work and finds her current boyfriend molesting two of her children.
And Novalee coming home from picking out a Christmas tree after realizing that her baby is five months old note 5 is an unlucky number for her to find out that her baby's been kidnapped by two religious fanatics from Midnight, Mississippi. In the beginning of the movie, she was abandoned by her boyfriend with no money and forced to raise her unborn child by herself.
X-Men: First Class: The Holocaust. The death of a parent, and the medicalized torture of an innocent child. All within the first 20 minutes. Then, for Erik, knowing that the people that killed your family and millions of others will go free unless you personally devote your life to hunting them down. A bit of a foregone conclusion, but Charles and Erik's "beach divorce", even though it's only a metaphorical divorce, (metaphorical) children having to decide which parent they're siding with in said metaphorical divorce, having a loved one be permanently disabled because of something you did.