"What Do They Fear?" Episode

"So suddenly everyone's having this big share-fest around the fire. Like Beth went on and on about how her mortal fear is being covered by bugs. Harold's afraid of ninjas, even Heather admitted that she's afraid of sumo wrestlers!"

—Gwen, Total Drama Island, "Phobia Factor"

An episode where the cast conspires to find out what one of them (usually, The Stoic) fears the most, setting up various scares. They often fail but the audience does learn the answer, greatly humanizing The Stoic in their eyes.

Related to Why Did It Have to Be Snakes?. Compare Your Worst Nightmare. May be part of Hiccup Hijinks.

Examples of "What Do They Fear?" Episode include:

Anime and Manga

In Full Metal Panic!: Fumoffu, the characters pay a visit to a Abandoned Hospital and Sousuke, completely unaffected by appearances of ghosts, zombies, and whatever, nearly freaks out in panic when it seems that Kaname has been injured.
In Ouran High School Host Club, the club members try to scare Haruhi and fail. It turns out she is only scared of thunder/lightning.
Ranma ½'s Ranma has one of these. They find out that he's afraid of cats.
Similarly, Inuyasha also has an episode dedicated to this trope, in which the whole main cast is trapped and forced to see their worst fears.
An early episode of Galaxy Angel revealed that Forte is deathly afraid of (and allergic to) rodents. Despite Normad's clear intent to use this for blackmail, it's never brought up again in the anime.
Yusei of Yu-Gi-Oh! 5D's is practically crippled by fear after losing his duel with Kiryu (once his best friend and Big Brother Mentor now brought Back from the Dead—which Yusei blames himself for—and psychotically evil), as if he's so unfamiliar with the emotion, he has no idea how to deal with it (dialogue Dub-Induced Plot Holes regarding visually non-existent entomophobia aside).
In an episode of Ronin Warriors, Dais revealed to Kento that the more he used his Hardrock Armor, the more bloodlust he would experience. Instead of being able to use the armor for good, he would use it for evil. For a while, Kento was afraid to summon his full armor in fear of hurting his loved ones. But when saw Yuli get hurt, he decided to push aside his fear, armored up, and defeated Dais.

Comic Books

Batman examples:
- Subverted in the Knightfall storyline. The Scarecrow turns his toxin on The Joker to discover what he fears. The answer: Nothing.
- In the same storyline, Batman's biggest fear is revealed to be Jason Todd's death - which already happened. Cue Unstoppable Rage at Joker.
- Really, this happens to everyone, heroes and villains, who comes into contact with fear gas. Bats has also been beaten with memories of his parents' deaths (in both The Long Halloween and Batman: Arkham Asylum); Catwoman had a good ol' wrestle with her relationship with Batman in Catwoman: When In Rome; and the Riddler is shit-scared of the Joker. (But then, so is half the DC universe.)
- Incidentally, if Blackest Night is to be believed, the only thing that scares Scarecrow is Batman. Literally, the only thing - using his fear gas so much has made Scarecrow not just immune to its effects but to feeling fear period. Except, as stated, the fear of Batman, to which there is no immunity.
- A unique example of this happens in the Catwoman story "I'm Only Happy When it Rains", which occurred slightly before Batman: No Man's Land. The Scarecrow (yep, him again) is using the chaos caused by the earthquake to test a new, more potent fear serum that only works on women, but all his "test subjects" die, literally scared to death by the experience.So he tries to capture a strong-willed subject, meaning Catwoman. However, Selina find the idea of facing her fears amusing, so she subdues his mooks and then uses the serum on herself. However, facing her fear is not what she expected, as it's dependency, the inability to function alone without help. The result is a unique character study on Catwoman that, like most stories like this, explores the darkest parts of her psyche.
- A crossover with Judge Dredd had Scarecrow using his fear gas on Judge Death. It seems Death is afraid of plushies.
This summer's Captain America (comics)/Thor centric Marvel Crisis Crossover Fear Itself looks to be one of these. The main plot involves Red Skull find the hammer of and resurrecting the spirit of the long dead of the Norse fear god. In the first issue as soon as Odin becomes aware of this he immediately tells Thor and the rest of Asgardians to pack their bags because they're leaving earth while they're still alive. Also, solicitations for tie-ins seem to indicate that there will be a lot of stories featuring the heroes of the Marvel universe facing their deepest fears head on.
In Elf Quest's Trial of Head, Hand and Heart arc, the Trial of Heart involves Savah mind-probing Cutter and Rayek to learn their deepest fears, and then setting challenges to see whether they can overcome them. The twist is that Cutter's challenge turns out to be Rayek's as well.

Literature

Harry Potter and the Prisoner of Azkaban has the third-year Defense Against the Dark Arts students taking on a boggart, a Shapeshifting creature which can take on the form of whatever its viewer fears the most. This provides a pretty funny chapter in which the students conquer the boggart by using the Riddikulus spell to turn it into something laughable, but it also shows the reader what some of the students fear most. Hermione, during her final exam, is terrified by her boggart, whose appearance (Professor McGonagall telling her she failed all of her classes) illustrates her deep-rooted fear of failure; Harry, by comparison, sees Dementors when he faces boggarts, which Professor Lupin says means that what he fears most is fear itself.
- There is a Tear Jerker echo much closer to the end of the series where Mama Bear Molly Weasley confronts a boggart who turns into her biggest fear - the dead forms of her beloved husband, her children, and Harry. This turns out to be the most heartbreaking bit of Foreshadowing in the entire series, since one of her children is killed by Voldemort's forces later.

Live-Action TV

Buffy the Vampire Slayer: "Fear Itself", as well as "Nightmares" in Season One.
- The season four finale "Restless" had this element too, being another dream episode (Willow gets her old stagefright dream from "Nightmares" combined with a scene where Buffy "unmasks" her as the timid girl she used to be, while Xander is berated by his father). There is a Call Back to "Nightmares" when Willow hopes that they are not performing "Madame Butterfly".
One episode of Doctor Who during the Third Doctor's tenure, The Mind of Evil, had him encounter a mental parasite that projected its victim's worst fear. His was the horrific memory of seeing a world burst into flames (from the serial Inferno). Later, the Master fell victim to it - his worse fear is the Doctor laughing at him.
- The Eleventh Doctor also had an episode of this, The God Complex. His worst fear is not shown, but the audience can hear the Cloister Bell ringing; and when he sees it, he is not surprised.
- Amy sees herself as a little girl, it is implied that her greatest fear is (once again) having to wait for the Doctor.
- They're shown their fears by entering the room which contains it. Rory, rather than being shown a room, sees an exit. Make of that what you will.
Whenever Barbas is the Demon Of The Week in Charmed, this is the basis of the episode. Well, he is the Demon of Fear.
Samurai Sentai Shinkenger does an episode in which Sixth Ranger Genta develops a crippling phobia of sushi after the events of the previous episode. Each of the other teammates confronts his or her own fear, some of which (Ryuunosuke's fear of cacti after sitting on one as a kid) are lamer than others (Takeru's fear of horror houses, which causes him to faint).
Several episodes of Maury have guests who fear really odd and crazy things, ranging from balloons, pickles, cotton balls, birds, mustard, peaches, and other things. Usually played at the expense of the guests where Maury brings out the stuff they fear and they go running scared for a while.
Sort of used in the M*A*S*H episode "Dreams", which feature the main characters' nightmares — all of which are highly tailored to the characters' histories and psyches.
An episode of Are You Afraid of the Dark? handles this, with one group member claiming to have exactly what The Stoic fears in a box. After the story is over (and The Stoic is incredibly rattled), the box is opened to reveal his biggest fear: nothing.
Chuck vs. the Aisle of Terror.
Life episode "Not for Nothing" turned out to be this.
Smallville's "Scare" involved an industrial toxin that caused everyone to experience their worst fear before falling into a lethal coma. Lex's was fun.

Video Games

A Temple in Star Fox Adventures had this, of course you have to get a Krazoa spirit to face your fears.
A bit of a Running Gag in the Paper Mario games, where the villain or one of their underlings will ask Mario or one of his allies what Mario is most afraid of, but will gladly accept that he's terrified of the normal items he'd been using the whole game.

Western Animation

Subverted in the The Legend of Tarzan. Jane spends an entire episode trying to find something which scares the titular character. In the end he freaks out over her powderpuff, however the last scene reveals that he pretended to be scared so she would stop trying to scare him.
Teen Titans, Episode 18, "Fear Itself" - The Titans pick up a horror movie called Wicked Scary. After watching it, they are scared out of their wits, although Raven refuses to admit this to the others. During the night, strange things start to happen in the Tower. Raven's suppressed fear acts out by using her powers to pick off the Titans one by one in increasingly nightmarish ways. Only by admitting that she was afraid is she able to regain control and free her friends.
Happens in Justice League, when Doctor Destiny sticks the core seven into their own worst nightmares. Superman was afraid of his powers going out of control and killing all his loved ones. Hawkgirl is trapped in a coffin and buried alive (this was foreshadowed earlier in the episode). Flash fears that he would run so fast that the rest of the world would freeze in time. Green Lantern is afraid that he was becoming nothing more than a tool for a ring, and losing touch with where he came from—reflected in people being afraid of him and being unable to communicate with him, as though it were just another of the alien worlds he's been tasked to protect. Batman cheats—despite telling Dr Destiny how "My mind is not a nice place to be" he just chugs coffee and stays awake until he takes him down, so we never do find out what he fears.
One episode of Total Drama Island had this... and their psycho host Chris tailor-made challenges for each contestant according to their fears. Courtney, however, had never told anyone her fear, though Chris was able to figure it out: green gelatin.
The Legion of Super Heroes episode "Fear Factory" had several Legionnaires confronted with their fears in a space station that feeds on their fears.
Pretty much every Scarecrow appearance in Batman the Animated Series went like this, but it was taken to its peak in "Over The Edge", in which Batgirl hallucinates her own death and her father turning against Batman, whom he blames for it. Add in the much scarier redesign of the Scarecrow for the last season and the voice of Jeffery Combs, and it's pure Nightmare Fuel.
- Of course, Batman can be Batman not only because of his conditioning and money but also because he has conquered his own fears and daemons. And if he comes across something he hasn't, he just plows on through anyway. Because he's...
- One time it was subverted; the Scarecrow made a gas which removed fear; causing people to engage in reckless and dangerous behaviors, putting the lives and limbs of themselves and others in danger. Unfortunately for Crane, this also removed Batman's aversion to using excessive force—he wasn't afraid of what killing a criminal would do to him...
Him once found out what each of The Powerpuff Girls feared the most and exploited them in a literal Your Worst Nightmare plot: Blossom, the leader, is afraid of failure (represented by failure in school); Bubbles is afraid of the dark, as had been seen before; and Buttercup, a la Raven, so vehemently prides herself on fearing nothing that the sisters' mutual minor fear of bugs and spiders makes her feel completely powerless.
The Dungeons and Dragons episode "Quest of the Skeleton Warrior" was one of these; the bulk of the episode was devoted to exploring the kids' fears to the point where the Skeleton Warrior himself pretty much got demoted to a walk-on.
An episode of Xiaolin Showdown did this; it consisted of Jack Spicer breaking into the Xiaolin temple and swiping a certain Shen Gong Wu that allowed him to enter the minds of the four main protagonists and find out what scared each of them the most. Hilarity Ensues when it is revealed that Omi, who normally prides himself on being the bravest of the group, is afraid of squirrels.
The Halloween episode of Lilo & Stitch: The Series focused on a experiment that could shapeshift into a person's deepest fears. Of them we learn Stitch is afraid of water (due to his creation excluding buoyancy), Lilo is afraid of Clowns (this from a girl who loves monster movies by the way), Jumba afraid of his ex-wife, Mertle and her posse Lilo herself (Though that could've been the costume she was wearing at the moment) and perhaps the most shocking Nani having Lilo taken away from her.
In the Extreme Ghostbusters episode "Fear Itself", the titular Ghostbusters encounter a Ghost who can manifest their greatest fears; Gothgirl Kylie is afraid of Maggots, Tech-Guy Roland is afraid of his own machines turning against him, Slacker Eduardo is afraid of Death, and gung-ho Paraplegic Garrett is claustrophobic, though he refuses to admit it. Also Slimer is terrified of... broccoli.