Joan: Are you — Are you being snippy with me? God is snippy. God: Let me explain something to you, Joan. It goes like this: I don't look like this. I don't look like anything you'd recognize. You can't see me. I don't sound like this, I don't sound like anything you'd recognize. You see, I'm beyond your experience. I take this form because you're comfortable with it, it makes sense to you. And if I'm "snippy", it's because you understand snippy.
And then there's Giant Naked Rei turning into Giant Naked Kaworu to get Shinji to calm down. He calms down all right... his A.T. Field collapses and he goes kersploosh inside his EVA. But he does get better. Sort of.
Aoba, however, experienced only a multitude of naked Reis, implying there was no-one he truly loved.
In Baccano!, the demon summoned aboard the Advenna Avis has taken to adopting a human form (which can be recognized as one of the supporting Camorra gangsters, Ronnie Sukiart). His true form is never shown in the anime, but the Light Novels imply that it's rather disturbing.
This shows up in The Melancholy of Haruhi Suzumiya, since the Data Overmind is of an existence completely alien to physical humanity, yet wants to discover what makes the title character able to do what she does; it has constructed humanoid Agents who can observe and interact. These Agents are partially their own being, partially of the Overmind. How exactly individual Yuki is in comparison to the Overmind is a common theme in the series.
However, definitely of this trope is Kuyou Suou, an agent of the competing faction the "Sky Canopy Domain". She has no individuality at all (at least according to Kyon); she's entirely a humanlike mouthpiece for the Domain. This doesn't quite make Kyon feel more comfortable, though, because Kuyou's horrible social skills (being unable to even talk coherently or look normal/visible) make the plan for them a failure in that respect.
In Hellsing Alucard, due to the thousands of souls inside him causing a lack of a definite gender, can change his appearance at will. To quote the man himself, "Form means nothing to me."
The wolves of Wolfs Rain spend most of their time as humans, even when they should be in wolf form (for example, when humans are no where to be seen, or when they ate a dead deer). Presumably this was because Most Animators Are Human and it was just easier to have their human forms be on screen. This is most likely a device to reinforce the fact that the "human form" seen by the world and the viewer is really an illusion. Very often, when the plot doesn't force the viewer to see them in a specific way (as people in the presence of people, for example), the viewer sees them switch back and forth: often very quickly from cut to cut.
In The Visitor, a one-shot manga by Kanno Miyamoto, a Shinigami explains that when visiting humans, he takes a form that would be comforting to that person. When he checks a file and sees that the dying man is gay, he notes: "That explains why I appeared as a man." So in this version, the Shinigami apparently have no control over which form they initially take.
Cerberus/Kero and Yue in Cardcaptor Sakura/Cardcaptors. At first they sleep mode as a stuffed animal and ordinary human but even after recovering their true forms they don't use them much. Probably because a large flying lion with some kind of helmet and a rather scary blueish angel would freak people out. The main cast, however, doesn't care. It serves a practical function as well, particularly in the case of Yue. Their true forms constantly emit magic (since both are the products of magic), which becomes dangerous if prolonged. This becomes a plot point in the "Sakura Cards" arc when a magic field prevents both of them from returning to their "borrowed forms" and Sakura has to come up with a solution.
Technically, Envy from Fullmetal Alchemist would count. He is a shapeshifter, and... well, his true form isn't exactly beautiful. Although in his case, it's because he is envious of humans, rather than wanting them to be comfortable. Truth takes this trope a step beyond: it wears YOUR body parts. So... a form you are uncomfortable with?
Shinigami in Soul Eater is in appearance a Lighter and Softer version of your classic Grim Reaper-type being. He states at one point he took on this look (and associated Cloudcuckoolander persona) in order to recruit children to his school, as his true form kept scaring them away. Thus he invokedDon't Fear The Reaper. When he loses said persona, it is an indication that he's either truly angry or simply tired of his staff mucking around.
Kid's human appearance could be seen as Shinigami deliberately invoking this trope, as it's a long time before Kid's nature becomes apparent, and by the time it does his True Companions don't care, they just see him as a friend.
Holo of Spice and Wolf is a wolf deity, and over 500 years old, but takes the form of a young girl. She says that the human guise isn't uncomfortable, but her real reason is because she's afraid of frightening off Lawrence. This very nearly happens anyway, as Holo is forced to turn wolf to protect an injured Lawrence. Lawrence reacts badly to being approached by a giant wolf, which in turn only alienates Holo further. Lawrence comes to his senses quickly, though, and manages to salvage the relationship. From then on, Lawrence seems comfortable with both forms, having learned that Holo is the same regardless of appearance.
To be fair, he's only see one demon's true form, which causes him to nearly lose his mind seeing it, and it did make him consider what Belldandy actually looked like. It also appears that gods and demons don't have too much control over how they look considering that Skuld is stuck looking like a kid, much to her chagrin.
Its the reason why the Scab Coral created human from Coralians to interact with humanity in Eureka Seven.
The Lord of Nightmares from Slayers can pick any form she wants, being god and all. She prefers to appear as a slender blonde woman though... at least, when she's not inside someone else's body.
This is also the standard skill for Gold Dragons (Filia, however, isn't very adept with it, with frequent tail-related Glamour Failures). Among the Mazoku, however, only the truly powerful can convincingly take human forms; middle-level Mazoku like Kanzel and Mazenda tend to have Red Right Hands.
The Seraphim in Itsuka Tenma no Kuro Usagi appear as a massive, statue like thing with lava veins and no face to speak of. Apparently, their true form would shatter reality. This doesn't stop Gekkou from talking down to them.
This may be a case of A Form They Are Comfortable With, since in Nyarko-San most of the aliens are big fansof human pop culture, and flashbacks show that characters like Nyarko seem to use their human form as their default even in situations where they wouldn't have to, and even characters who don't care about humans (like Nyarko's older brother Nyar-O) take on human form when on Earth.
Subverted with Heartseed in Kokoro Connect. He often takes over their teacher and club advisor, Ryuzen Goto, when he wants to speak to them. While Goto-sensei is indeed a laid back and nice guy, in Heartseed-mode, he appears rather creepy due to making the guy looked drugged out, and speaking to them with a monotone voice. It also doesn't help that when several of the characters attempt to attack him, he can casually block, counter, or evade their attacks.
Izanami, ruler of the underworld in Kamisama Kiss, takes the form of Nanami's rival Kayako when she appears before her since Izanami's own form rotted away long ago.
Orochimaru, a major antagonist from Naruto, reveals to his former sensei, the Third Hokage, that he has been using a technique called Living Corpse Reincarnation to transfer his soul into a different body once every three years. As expected, the Third Hokage is horrified by this revelation when Orochimaru shows him the true face of his host's body which comes off as completely unfamiliar to him.
Backfires on Space Pirate Mito, a small childlike alien who uses a high tech "Mail Suit" (AKA the "mom suit") to look like an adult human woman. She tries to re-use the suit after accidentally revealing her true form to her half-human son Aoi hoping it will convince him to call her "Mom" again, but now that he knows the truth Aoi finds the suit even more disturbing than her true form.
When appearing to his lover Nada, Morpheus himself takes on the form of a tall, African man covered in tribal markings. He did a very smooth statuesque thing with Augustus Caesar, and got mistaken for Apollo, about which he was rather snippy. Morpheus and the other Endless have a different appearance to each person that looks at them (the one we see seems to be the default British/American Caucasian version, though the art style shifts all the time because different artists came in for different chapters.)
Marco Polo: Are you always so pale? Dream: That depends on who's watching.
Dream also appears as a black cat to cats, black fox for foxes and a blackened face inside a fire vortex to the Martian Manhunter. The conceit is that people see the Endless as being either like themselves or like what they expect.
Dream seems to go back and forth with this: half the time he wears period clothing, but he sometimes shows up in the human world wearing ridiculous capes and things, which have drawn comments from humans who run into him. John Constantine complained about the Robe of Flames being embarrassing, so he put on a black trench coat. John then complained about no sense of humor.
This trope was also explicitly mentioned by caliph Harun al-Rashid when he tries to summon Dream and demands that the lord of dreams shows himself to the caliph in a form Harun will be comfortable with.
When done by others:
During the Season Of Mists storyline, Lord Kilderkin of Order manifests himself as the supreme icon of order - an empty cardboard box.
Likewise, the Chaos Lord called Shivering Jemmy of the Nightmare Brigade manifests as a three-year-old girl, complete with a balloon and a love of ice cream.
Jemmy: Nobody clever bes boxes!
Gilbert, a rotund and helpful middle-aged man, was a manifestation of Fiddler's Green, an intelligent place that inhabited the dream realm. Also, he looks and sounds very much like G. K. Chesterton.
Cain And Abel also qualify. It's heavily implied in A Parliament of Rooks that they weren't the first human murderer and victim, but in fact the first murderer and victim in the entire history of the universe and their true forms are actually Starfish Aliens. Also, they aren't really related to Eve, who may or may not have ever been a real person to begin with, let alone whether or not she was really human.
Invoked when Delirium actually mistakes a goth-dressed (lesbian) human for her sister Death in the beginning of Brief Lives. (It's unlikely any of the other Endless would mistake a human for one of their own, but Delirium and reality are not always on speaking terms.)
Lampshaded when Orpheus pays an unexpected visit to Death in Fables And Reflections, catching her dressed down. She changes her twentieth century apartment, complete with a teddy bear, a fish-bowl and discarded stockings followed by a t-shirt and jeans clad Death, who promptly replaced it with stone columns, eternal gloom and her wearing a black Gorgeous Period Dress and a veil.
In the Lucifer comics God appeared to Elaine in the form of her loved ones at first, and when Elaine told him to be someone she didn't know chose to appear as an elderly British gentleman in a bowler hat. He appears content to stay in this form for the rest of the comic after that, something Lucifer comments upon.
The "out of continuity but very much inspired" Murder Mysteries had God disguised as a strange wingless angel, which the protagonist comments had eyes that seemed to contain more than the others as one of the first hints to his real identity. Oddly enough, once revealed as being God himself, he is never shown in panel, despite no evidence of any transformation taking place.
Galactus and other Marvel Comics "higher plane of existence" beings look humanoid to us, but that's just our filter. Most of them "wear" temporary bodies when visiting the material universe, made to order for them by a being called Antropomorpho. Despite this trope, they're almost always shown in the same individual forms. Galactus, however, doesn't have such a temporary body. Instead, his own form looks different to different viewers; for instance, a Skrull sees him as Skrull-like. (Galactus's original form as a mortal being in the universe preceding our own, however, was indeed humanoid.) One issue featured a scene where humans and dozens of aliens gazed upon him at once, the frame was filled with smaller images representing what each of them saw him as.
God him/her/it/none-of-the-above-self appears to the Fantastic Four as Jack Kirby. Or isJack Kirby. It's not clear.
Jack Kirby created the Fantastic Four and several other characters in Marvel, so to them, Jack Kirby IS God. And since he did the same for several characters over at DC, so perhaps over there he is also God.
In Adam: The Legend of the Blue Marvel, The Watcher turns into a black man in order to talk to the title character. Humorously, the Watcher only did so because he misinterpreted Blue Marvel's joke about finding a white man on the moon.
One time-travel adventure for Tom Strong sees him encounter one his recurring enemies, The Pangean, who generally takes the form of a giant slime mold (who at this point, is roughly the size of a small country). Reasoning that Tom would rather speak to a biped, he splits off a part of his biomass, forming it into a shape resembling a green man wearing 17th century style clothing so that they can communicate more easily.
Implied by Whatever Happened to The Man of Tomorrow? as the reason for the fifth-dimensional trickster Mr. Mxyzptlk's usual form as a little man in a purple suit, when he mocks the characters for thinking that's what he actually looks like. Narrating the story years later, Lois Lane describes being confronted with his true, hyper-spatial form: "I can't describe what Mxyzptlk then became. He had height, width, depth... and a couple of other things". Within the comic, he's drawn as a gigantic energy being.
Lampshaded and justified by CrossGen when Ilhan of Meridian visits Ingra of The First. Ilhan balks at her Stripperifficdefaultoutfit, and Ingra amusedly transforms it into a more modest beige gown for his comfort, taunting him as she does so.
Variation: In Proposition Player, Bill the Angel of The Lord claims he uses that name because were he to speak his real name, the sky would rupture, the oceans turn to blood, a thousand virgins die, etc., etc. Given that he's a bully and leg-breaker for the forces of Heaven, it's not certain whether he's sincere or just being an egocentric jerk.
In one issue of Fantômas, the thief/hero tries to steal a unique duck-billed dog. It turned out to be an alien sent to Earth to study humanity, who tried to take the form of a dog to go unnoticed, but something went wrong with the process. At the end of the story it changes into an eagle instead, this time more successfully.
In Powers, the aliens who direct the Millennium Corps appear to Walker in human forms, most commonly those of Zora and Retro Girl. A subversion in that Walker has made it clear that he is not comfortable with them taking on the shapes of his dead friends and lovers.
Hellblazer; John's original dealing with his long-term enemy Nergal dealt with this. His summoning demanded Nergal appear in a form pleasing to the human senses. So Nergal took over the body of a little girl. Then it got worse.
In Runaways, Xavin deliberately shapeshifts into the form of a human teenage boy when he first meets Karolina, believing that it's something that she'd be comfortable with. When she's shocked by his appearance, s/he figures that her parents prepped her for him/her arriving in his/her natural Skrull form (really, she's surprised at the fact that her parents promised her hand in marriage to him/her.) When Karolina reveals that she's a lesbian, Xavin takes the form of a human teenage woman, a form which s/he stays in most of the time when around Karolina. For the few times when Xavin thinks it's more helpful to be in a male form, Karolina does not interact romantically with him/her ("If you were a girl right now, I'd kiss you.")
Inverted during the "Dead End Kids" arc, where Xavin assumes a white male form for most of the team's stay in 1900s New York, as s/he assumes that she'll experience less problems that way. Karolina comes this close to dumping her over it.
God, in Lenny Henry and the Quest for the Big Woof, appears as a slightly geeky white guy, in green-tinted glasses and Joseph's dreamcoat. When Lenny questions this he says he could manifest an explosion of white light, but "Who'd want to sit behind this at the cinema?"
When, after being exposed to the Terrigen Mist, Kamala Khan receives a vision of somone or something calling themselves "faith". The form they appear in? Captain Marvel, Iron Man and Captain America. This surely tells us something about the girl.
In the Neil Gaiman iteration of The Eternals, the Dreaming Celestial takes on Sersi's form to communicate with Makkari. After he complains that it's kind of creepy having the Celestial's voice come out of her mouth, the Celestial puts its face on her body, which Makkari finds even creepier.
In one GarfieldStory Arc, Garfield's conscience took the form of Garfield's food dish for this reason. (He really looks like everyones mother.)
In Aeon Natum Engel, thanks to the Cthulhu Tech legacy, there are variable auto-censors that automatically render images (in real time) in ways that are deemed to be less harmful to the human psyche. The most common appears to make video look like something from an anime.
Some Naruto fanfiction show the various bijuu choosing to assume human forms in order to communicate with their containers. Whether the bijuu are more sociable or not varies from author to author, but the Kyuubi almost invariably ends up being a redheaded womanwith a model's body. Following Kyuubi appearing female, cue standard speech about "You think a female can't be strong?" from the demon. The fact that bijuu are living masses of chakra with no actual physical form, and thus no gender, is conveniently ignored.
The Melt has the Kyuubi appear as a Sharp-Dressed Man in black with slicked red hair. Upon Naruto saying "I thought you were a fox.", the Kyuubi shows his true form promptly scaring Naruto and the Kyuubi to point out that he chose that form for a reason.
Played with in With Strings Attached. The Fans look like featureless human mannikins to the four, but that's because they're stuck using standard humanoid telepathic avatars; they aren't especially worried about what the four might think of their real forms.
"So what do'' you two really look like?" Ringo asked again. "Not as pretty as you guys," said Varx. Shag elbowed him. "Shut up, Varx! We're not human, Ringo. We'd show you, but we don't have the ability here. This is a preset background with limited variability, so we're stuck with these avatars. But we're kind of... um...." "Kinda lizardy, kinda birdy," Varx said helpfully. "With claws," said George. "Yeah."
A benign version in Strings, when Korra reaches Avatar State after being forced to return to Tarrlok,Aang appears to Korra as his twelve-year self.
It's also implied that the princesses do this as well, as when they fight Nyarlathotep outside reality, they take on forms of pure power that no pony would recognize as them.
Played with in Son Of The Warp. A Lord of Change sent to mentor Joseph tries to invoke this by taking the appearance of Chiron. Joseph actually finds this uncomfortable, and instead orders the daemon to take the form of Winston Churchill.
Defied by Havoc, Discord's father, in the Dark World Series of the Pony POV Series. Rancor, Discord's little sister, says He was going to drop her off personally using an Avatar, but didn't because He was outright trying to avoid this trope and couldn't decide if His pony Avatar was still scary due to being 'outdated' or more scary due to Uncanny Valley. Considering He's the Anthropomorphic Personification of Mass Hysteria, this makes sense. During Starlight's trial, He assumes the form of an alicorn version of Starlight, but this is less for her comfort and more to appeal to her ego trying to win her soul.
The Father of All Alicorns also averts this, as the few times we've seen Him, He doesn't bother to disguise Himself, even though His true form is rather confusing. This may be because His presence is naturally comforting, so he doesn't see the need. When He appears in Starlight's trial, He assumes the form of a colt, but that was presumably because His true form would've tipped Starlight off as to which side was on her side.
In Legend Of Korra fanfic Strings has a rare human example with Korra and Aang. When Korra finally achieves Avatar State, Aang decides to appear as his twelve-year self. He does to not scare Korra, who is a Domestic Abuse victim, and take her mind off her troubles by playing games with her.
Films — Animation
God in The Prince of Egypt manifests Himself as a burning bush. He also speaks to Moses with Moses' own voice. There's some precedent for that in the novelization.
In Disney's Aladdin: The Return of Jafar, Jafar's true form of a huge red Genie is too much for thief Abis Mal, so Jafar spends most of the film looking as he did while human. Which only helped a little, since let's face it, even human Jafar is pretty damn intimidating.
Films — Live-Action
In Oh, God!, God specifically tells Jerry Landers that he could have appeared in any other form, but chose one that Jerry could understand. God does the same thing in the two sequels. And both times, he looked like George Burns. So did The Devil. Which stands to reason, since God specifically tells the protagonist, who just thought the Devil was trying to trick him, that Harry O. Tophet (H.O.T., get it?) always wants to look like and sound like him.
One of the Sufficiently Advanced Aliens in Contact takes the form of Eleanore Arroway's dead father in order to be able to talk to her. The Caribbean beach upon which they hold said conversation is also an example of this trope. Everything she saw outside the capsule after entering the second wormhole was previously shown in the film, implying that she was in some kind of VR from that point until she was returned. The alien's "unfocused" form implies that it's a tall Gray Alien, similar to the one in Close Encounters of the Third Kind.
In Mr. Destiny, Fate itself manifests to Jim Belushi as a bartender who looks a lot like Michael Caine.
This trope is the entire point of the Metatron's existence in Dogma.
"Human beings have neither the aural nor the psychological capacity to withstand the awesome power of God's true voice. Were you to hear it, your mind would cave in and your heart would explode within your chest. We went through five Adams before we figured that one out."
God also does this, spending most of the movie in the form of a middle-aged homeless man in a coma, and at the end appearing as Alanis Morissette.
Terminator Salvation has SkyNet take the form of Dr. Serena when she debriefs Marcus in his role as her Unwitting Pawn. To add extra creepiness to the "kindness", she offers to switch her appearance into that of John Connor or Kyle Reese... as she is having both killed mere floors below! Needless to say, this was not a successful persuasive tool. Oh, and her eyes turned red like a Terminator's do.
Likely in an homage to this trope's use in Star Trek, the Thermians in Galaxy Quest disguise themselves as humans when visiting Earth. Their native form looks more like a mollusk than a human. In one scene, the Thermians forget to put on their disguises when visiting the Show Within a Show's stars — causing the latter to be quite disturbed.... They also keep up the disguises when no humans are around, because their slavish devotion to the Galaxy Quest "historical documents" made them build the ship exactly as they saw it — i.e., with controls designed for human beings. In their true forms, they can't use their own ship!
The title character in Starman takes the form of Jenny Hayden's recently deceased husband for exactly this reason.
The situational variant of this is used in the first movie. David Bowman travels through the Star Gate, which we presume is even more mind-blowing in the flesh, so to speak, and ends up... in a hotel room. Not only that: in the novel, Dave notices that it's a bad rendition of a hotel room. It might look okay on the surface, but he quickly finds out that he can't open any drawers, the books are painted on the bookcase and all food and drink containers, such as cereal box and beer cans, are filled with some spicy, blue stuff that smells like macaroons. It's as if someone was trying to imitate a hotel room without understanding it. He finally finds out why when he turns on the TV and sees the same room in an old soap opera on the screen. The aliens had based the room on what they had learned from various earth broadcasts. But then again, it is the result of the trope being played as straight as possible. It never was the idea that Dave should take residence in the room; its function was merely to calm him by placing him in a familiar environment, in order to prepare him for his transformation into the Star Child.
The Monoliths themselves are often described as having a dimensional ratio of 1:4:9; or at least it does in dimensions that we can actually see. Dave Bowman heavily implies that every Monolith encountered is actually the same one and that despite appearing from several feet to several miles in length, it has only one size, "as large as necessary".
Santo vs. la Invasion de los Marcianos (Santo vs. the Martian Invasion): The Martians are human-shaped to start with, but decide to run themselves through a transformation machine to get more human bodies. This meant they wouldn't have access to their Death Ray Third Eye while in human form ... but that's good, because now the scriptwriters don't have to try explaining why Santo doesn't get vaporized when he goes mano-a-mano with them. Being able to ditch the long blond wigs probably made life easier for the wrestlers playing Martians.
It Came from Outer Space (1953). The aliens can copy human form; naturally this only serves to freak out those humans they're trying to reassure about their peaceful intentions.
Inverted in Avatar, it's the humans who take on the form of aliens in an attempt to begin diplomatic negotiations with them while they plan to destroy the planet. Inverting this trope was the main thrust of Cameron's original script, in which the Na'vi are Starfish Aliens. (Sully still falls in love with a Na'vi in his Avatar form.) The avatars are still different from the Na'vi, being Na'vi/human hybrids. They have smaller eyes and ten fingers and ten toes (the Na'vi have eight of each). Presumably, this is because a human wouldn't know how to function with only four fingers on each hand. Though they seem to have no problem getting used to the tail...
The recent Percy Jackson and the Olympiansmovie adaptation has Hades, whose style resembles Mick Jagger's. When Percy, Annabeth and Grover are a little bit surprised by his appearance, he shows them his true form — a big, talking flame — and changes right back. His looks aren't discussed any further. The humanoid version is implied to be closer to his true form — the flaming-demon-shape was just a form he picked to make them uncomfortable.
This trope was weaponized in Dreamcatcher. The true form of the aliens is a massive, tripodal creature that can devour humans; knowing that this form will instigate aggressive reactions, they project a telepathic image of the traditional Gray alien into human minds, making them appear weak and near-human.
Winston: I thought Gozer was a man. Egon: It's whatever it wants to be.
Zarkorr! The Invader has a man who is judged to be the median of human society, chosen to prove his species's worth by (somehow) defeating the titular monster. The one who relays this challenge to him takes on a form that is made to be "familiar and unthreatening". In the protagonist's words: a "tiny, teenage mall-tramp."
Similar to the example from Dreamcatcher, the aliens in Progeny project the Gray form to make the abduction ordeal more comfortable for humans. Their real form, as revealed part-way through the movie, is horrific, non-humanoid, and vaguely reptilian.
Nyarlathotep, however, does hide in the ever-so-subtle form of... an Egyptian Pharaoh. He also likes to fuck with people's heads by sticking to the bare minimum. The reason one of his masks is known as "the Black Man" isn't because it appears to have African features, but because its skin is pitch black. He does not always appear dressed as a Pharaoh; in Nyarlathotep he is described only as a swarthy man "of the race of the Pharaohs" — from Lovecraft's letter:
Nyarlathotep was a kind of itinerant showman or lecturer who held forth in public halls and aroused widespread fear and discussion with his exhibitions. These exhibitions consisted of two parts — first, a horrible — possibly prophetic — cinema reel; and later some extraordinary experiments with scientific and electrical apparatus.
The Mist is used to blur the perception normal people have when witnessing demigod events. For instance, in The Lightning Thief, during the showdown between Ares and Percy on the Los Angeles beach, they have swords but bystanders and LAPD officers think they are having a gunfight. It causes a Gas Leak Coverup event afterwards since it is said that Ares "fired" a shot that caused an underground gas line to rupture and blow up several police cars — in reality Ares waving a fireball at the cruisers.
In The Last Olympian, Percy believes that the reason Mrs. O'Leary is not noticed while bounding through the busy streets of Manhattan at mid-day is because the Mist makes them mistake her for a semi truck.
Chiron can choose to appear in a wheelchair instead of Centaur form depending on what he feels like.
Near the end of C. S. Lewis's Perelandra, two eldila attempt to find a suitable form to take when they meet the king and queen of Perelandra. Good thing, too, as their first two attempts wouldn't have worked at all. In particular, one of those forms is described as being a particular perception of the eldila in much the same way as suffering a concussion and seeing stars is a particular perception of a rock (i.e. one that has been thrown at your head).
C.S. Lewis also explores the idea in an interesting way in The Chronicles of Narnia. Aslan the talking lion isn't just a Crystal Dragon Jesus, he actually is Jesus. Or rather, on Earth, among humans, he went by that name and form, while in the Talking Animal world of Narnia, he manifests as a fellow talking animal.
Yet another C. S. Lewis example is in the finale of The Screwtape Letters. Screwtape is reaming Wormwood for allowing his patient to die, and in his beautifully goosebumps-inducing description of what it is like when humans encounter God after they die, one of the things he says is that God "wears the form of a man."
In a short story by Margaret Attenborough, when God visits Kitty Heaven (which is actually Human Hell) he takes the form of a white Persian.
Abstract example: Stanislaw Lem's Golem (an artificial intelligence of the 14th generation) is pure intellect and has no personality whatsoever. When it gives lectures at the M.I.T. for a while, it is forced to assume a personality (an eloquent and apodictical preacher) so the humans can at least begin to accept it as an interlocutor, even though both sides are perfectly aware of the pretense.
Humorously played with in a science-fiction story (name sadly forgotten) where a dead human whose casket is launched into space is brought back to life by a group of aliens. The main character/narrator asks the alien why it looks so human-like, to which the alien gives the standard response. He asks to see its true form, and when the being complies, the narrator notes for the audience that he "wasn't sure which end to talk to."
The Ellimist takes the form of a girl known by the Animorphs when he humbly requests their help. As he also stops time along with this, Jake thinks to himself that it's not really all that humble. Most of the time, he appears to the Animorphs (and Elfangor, in the 80s) as an adult male, or a wrinkly elf-like creature (as seen on the cover of The Ellimist Chronicles). At the end of The Andalite Chronicles, Elfangor sees the Ellimist as he truly is: "An indescribable being of light and time and space."
When the Ellimist appears to Tobias in The Change, he appears as a mixture of birds. "I saw it flying toward me. It was a bird of prey. A raptor. Some undefinable shape, part falcon, part eagle, part hawk. It had a snow-white belly and reddish-brown back and a tail that spread to show a dusky rainbow of colors." When Tobias comments that this wasn't how the Ellimist looked the last time the Animorphs saw him, the Ellimist says that he chose a shape Tobias would identify with.
Near the end of Carl Sagan's novel Contact, the main character encounters an alien being that has taken the form of her long-dead father in an attempt to make the experience less frightening. The other characters encounter something similar. One person sees his granddaughter. Another sees her long-dead husband. And the Chinese archaeologist sees Confucius.
Wheeler, an alien of some kind or other beyond human understanding in the books Signal to Noise and A Signal Shattered, by Eric S. Nylund takes on a sort of human form. He takes on the form of the protagonist, Jack, except for perhaps some odd little differences such as the spinning gears in his eyes.
In Harry Potter and the Deathly Hallows, after being "killed" by Voldemort, Harry finds himself in an Afterlife Antechamber that looks like King's Cross Station. Dumbledore, who meets him there, is a bit surprised by the description, but says it's what he can cope with. When Harry asks if he has to go back, Dumbledore extends the metaphor: he could, if he wished, metaphorically catch a train. "Where would it take me?" "On."
Played with in a Judge Dredd spin-off novel, Wetworks by Dave Stone: An alien adopts the form of a certain famous cartoon character in an attempt to make the humans it deals with more comfortable; it doesn't really work, partly because seeing a cartoon character in the flesh is actually pretty discomforting, and partly because although the alien's shape has changed it neglected to do anything about the fact that it constantly emits a toxic gas.
Subverted in Solaris by Stanislaw Lem, where a planet-sized alien intelligence spawns human replicants convincingly interacting with the protagonists, while the purpose of this phenomenon and the message, if any, behind it are a maddening enigma.
Isaac Asimov used this in a number of his short stories. Notably in "Buy Jupiter", where aliens who inhabited the coronas of stars (and thus existed at temperatures in the thousands of degrees) interacted with humans by projecting human forms to Earth. The humans are fully aware that they are talking to simulations.
Mirror Girl from Blind Lake adopts the image of little girl Tess in order to talk to humans.
In Neuromancer, Wintermute speaks to the main character through cyberspace and takes the forms of people from his past. Largely because he lacks a personality of his own, adopting that of others is the only way he can communicate with humans. Neuromancer on the other hand, has constructed a personality for himself, and takes the form of a 13-year old Brazilian boy.
Parodied in John Dies at the End by David Wong. When traveling to another dimension, the inhabitants there greet them completely in the nude for fear of appearing otherwise would disturb the visitors. They couldn't be more wrong.
In Otherland, Jongleur tries to force this on The Other through the use of computer simulations. However, it's alien enough and has enough control that the simulation always warps into something disturbing. It may be telling that he ends up preferring to communicate with it as Anubis, while it whispers to him from a coffin.
The angels in His Dark Materials have a true form which is apparently something like architecture, but humans and panserbjřrne (and others) see them as Winged Humanoids because their mind just can't wrap itself around their true forms. Technically, the angels aren't even taking this form, the mind of the observer just interprets them as looking like angels. This even applies to witches, who have much more expanded minds than other races and were aware of things like parallel universes long before them.
Explored extensively in C.S. Friedman's The Madness Season. The forbearer-type aliens called Saudar went to immense efforts to tame and enslave the inherently formless beings known as the Mara, who could not only adapt themselves to any shape, but could analyze the brain of the shape they took to immediately become fluent in spoken language, body language, and given enough time, social and cultural nuance as well. They went to all this trouble because, as we find out towards the end, the Saudar were ugly as sin and would not have been accepted by any alien race they encountered; they needed the shapeshifters to act as their ambassadors.
In Glen Cook's book Petty Pewter Gods, it turns out that practically all of the gods of the various pantheons are actually refugees from another dimension that feed on faith. Their true form seems to look something like a giant glowing sea anemone — or at least, that's the form of something that tries to break free and into the real world.
In Cruel Zinc Melodies, a mysterious presence that's really a miles-long sentient fungal mass under the World Theater's construction-site sends a projected image of Eleanor to communicate with Garrett.
The Seleneans; in their natural state they are only semi-humanoid at best, and rather ferocious-looking. The Selenean Pod Mothers, who have great control over their offsprings' genetics, have bred certain broods designed specifically for offworld contact. These individuals, Y'Lira Modan of Star Trek: Titan among them, take a form more pleasing to humanoid eyes, but retain the ability to shift into their natural state if need be.
Inverted in the Star Trek: The Next Generation novel Eyes of the Beholders. The Enterprise encounters an artifact of an extinct race that is sending out a psychic beacon that causes insanity with prolonged exposure. It's so oddly shaped that they can't look at the thing, and beaming aboard it overloads Data and sends Worf on a homicidal rampage. Although they deduce that it's the cultural legacy of an extremely unique race (it was a spacefaring art museum with psychic advertising) Picard orders it to be destroyed, before they realize that they can reprogram Data to be comfortable enough with it to go in and turn it off.
Subverted with Reketrebn in Doug Naylor's solo Red Dwarf novel, Last Human. As a Symbi-morph, it attempts to please Lister by appearing as Kochanski. He tells it not to, as he is missing her deeply. Reketrebn takes Rimmer's form, which Lister definitely doesn't want to see. As a result, Reketrebn takes on its neutral form unless required for practical reasons (such as appearing as Kryten will allow Lister to access his subconscious, as Lister generally knows what to do, but consults Kryten as he lacks confidence in his own intelligence).
Senna has her astrally-projected form take the form of a military-looking man when communicating with her followers, wisely suspecting they would find that more authoritative than a pretty sixteen-year-old girl. When she actually brings them to Everworld she eventually creates the illusion of herself as a pseudo-Valkyrie for the same reason.
Dionysus also admits that the gods (at least the Olympians) do this, taking whatever form they feel suits their particular profession; he, for example, goes for a more "approachable" look since he enjoys mortal company. When Christopher questions why Artemis (goddess of virgins) would choose to look attractive, Dionysus replies that a pledge of eternal chastity wouldn't be worth as much if men didn't want to have sex with her.
Zeus is so overwhelming that seeing him will kill a mortal (referencing the Semele myth). He talks with mortals by first taking some other form (first an eagle, later a bull) and slowly easing himself into a more humanoid appearance. April notes that she has to look away as he does this, since looking for too long feels like staring into the sun.
In the Dumarest of Terra book Prison of Night, Dumarest meets with a Hive Mind. It takes the form of a religious leader he'd known years before, stating that the hive has assumed this appearance because "the shape is one you find comforting and trust." Dumarest isn't a very trusting person, so this is a strong statement.
ConSentiency has interfaces in the "Beachballs" as the main means for contact with a Caleban — very tenuous, between barely understandable speech and apparently meaningless visual representation. But it turns out this counts as a quite good job, considering the scale of the problem.
McKie: And all we see here is this... this bit of nothing. Caleban: Not put something here. Self-I put something here and uncreate you. McKie discontinues in presence of I-self. McKie: Do you hang that, Tuluk? Tuluk: Hang? Oh, yes. She seems to be saying that she can't make herself visible to us because that'd kill us. McKie: That's the way I read it.
In Ilona Andrews' Kate Daniels' series, there's a shapeshifting infodealer named Saiman who uses his ability to physically become any man or woman he can imagine in his efforts at ferreting out information and for various social dealings. When he's doing his thirty-six-hundred-dollar-an-hour infodealing business (which, truth be told, he's worth the price because he gets results) in the comfort of his own home, he chooses to look like a pleasant, intellectual fellow approaching forty. The trope is subverting, too, as Saiman really doesn't like his own natural form — a pure-white-skinned, ice-green-haired brutish looking absolute brick of a bruiser who's incidentally about eight and a half feet tall. See, Saiman owes his shapeshifting powers to his heritage. He is one-half ice giant, one-quarter human, and one-quarter god. Specifically, his grandfather is Loki. And he doesn't feel his muscles-like-rock exterior matches his genius interior. So the various striking appearances he crafts — striking men and beautiful women, depending on what he feels is appropriate — are all an effort to make a form he himself is comfortable with.
Subverted by Aphrael. Although she is a goddess, she chooses to appear as a barefoot little girl — not so much for the comfort of the humans with whom she interacts, but for her own. She likes to be cuddled and kissed and treated like a little princess, so she adopts the form that is virtually guaranteed to win her such treatment. Her true form isn't that difficult to get around — a gorgeous, pale, nude young woman. Who glows. And flies. And is a source of magic. And can destroy you with a thought, if she feels like it. The only reason Sparhawk isn't comfortable with her true form is her nudity goes against his gentlemanly propriety.
Also, by the time he first sees her true form she's already assumed a new disguise form as his daughter, so naturally seeing her as a beautiful naked woman is a little off-putting.
Played straight in The Tamuli trilogy with Xanetia. The most skilled of the Delphae, when she ventures outside her city, she alters her natural light emission to make herself look like an ordinary Tamul. This is not so much for the comfort of the heroes who are by this point used to the idea but rather for the general public since the general reaction to seeing a Delphae (better known as the Shining Ones) is to run in terror.
The Arisians. Mentor, in particular, has manifested as a giant brain in a jar, a giant brain not in a jar, a hard-bitten detective, a university professor, and a seven-foot woman. Though, given how the Arisians work, this may be less "A Form You Are Comfortable With" and more "A Form That Will Elicit the Desired Reactions". In any event, they don't achieve this by taking physical forms but rather by projecting the desired forms as mental images to their audience.
Played straight later when one of the Lensmen encounters an Eddorian. The Arisians, knowing that even a second-level Lensman looking upon the true form of an Eddorian will go mad, "disguise" the Eddorian as a giant brain-thing and pass it off as a renegade Arisian. The third-level Lensmen who later encounter Eddorians presumably get the full experience, but they're also mentally equipped to handle it, having minds that (at least in potentia) surpass the Arisians' own.
In Childhood's End by Arthur C. Clarke, the Overlords hide their true form (they look like classic demons) for a long time, because they know that we will not be comfortable with it.
In The Dresden Files book "Ghost Story", Harry starts out the book in a place that's "in-between" the normal world and the afterlife, possibly some sort of limbo. When he asks one character there what's going on, Harry is told that he's "allowed to see as much as he can handle".
Flatland: A Romance of Three Dimensions, features an interesting variation of this trope. As the Square passes through Lineland, the king of Lineland can only perceive the Square as another Line. When a Solid passes through the plane of Flatland, the Square can only perceive the Solid as another Shape.
In Luke Skywalker and the Shadows of Mindor, the rock-inhabiting energy beings humans call Melters have none of the same senses humans do, but sense the slight electricity in human bodies. Luke is known for being able to communicate with anything, but when he tries to communicate with Melters he has to perceive the world the way they do, and it's too alien for him to be able to make sense of it. Instead he interprets the experience as floating in space, with himself and all other lives, including theirs, as different stars. He's aware that it's a metaphor and that if he stretches it too far it's just not going to work.
In the Illuminatus! trilogy, an entity presumed to be the Devil manifests at the climax of a memorable Black Mass. The defrocked priest (defrocked for detrousering altar boys) Padre Pederastia, screams Come not in that form! as the entity begins to appear. Bidden to come in a form we can be comfortable in seeing, the form in which you move and go about your business in the world, the entity complies. He adopts the form of evangelist Billy Graham.
"Tomorrow and Tomorrow" by Charles Sheffield has its protagonist awaken in the insanely-far future, where most sapience has existed in the form of computer software for untold ages. The locals have no clue how to communicate with the uploaded copy of a 20th-century mind, and he has to teach this trope to them simply to avoid having his mind shattered. All the story's 'characters' from there onward are instances of this trope, technically including the protagonist himself.
The Web Serial NovelThe Zombie Knight features reapers who act as Psychopomps for the dead. The reapers are basically imaginary. They don't have a "true" form and those who can see them perceive them exactly as they expect a reaper to look.
In Seraphina dragons must stay in their saarantras around human territories.
The Android's Dream by John Scalzi features an example of "a form we're both comfortable with." Two characters interacting in a cybernetic mindscape (one which is otherwise abstract rather than a reality-mimicking "Cyberspace") shape themselves a nice little garden to chat in, and human "bodies" to chat with.
In Ghostmaker, an Eldar Farseer requires the aid of Rawne's Ghosts to defend a lost webway gate, but doesn't want the Eldar presence to be known to them. So, he uses his psychic abilities to produce a sort-of Lotus Eater effect, making them believe that they're on Tanith fighting alongside other Guardsmen against the forces of Chaos, when in reality, they're fighting through the ruin and the Guardsmen they're fighting alongside are actually Dire Avengers. The masquerade isn't very convincing and it's eventually broken by the Ghosts themselves.
This happened a lot in the various Star Trek series:
The original Star Trek series featured Trelane ("The Squire of Gothos"), the Organians ("Errand of Mercy"), and the Metrons ("Arena"), all of whom took human form in order to interact with the mere mortals.
Every time a member of the Q Continuum visits the USS Enterprise, the Deep Space 9 station, or the USS Voyager, this trope occurred. Often, the Q in question would make some sort of snarky remark about having to wear a meatbag suit while doing it. And like the example from Contact above, when the crew of Voyager was taken to the Q Continuum itself, the appearance of this place was a version of this trope because the true nature of the Continuum is beyond the safe limits of mortal comprehension.
In a couple of novels, Q tries to expand Picard's horizons; one time he has them take the form of a 3-headed serpent, but it's too much for Picard; another time, when he takes Picard and Data to the Continuum, the unfiltered sensory perception of the Continuum makes Data shut down.
And adding to the mystery of how the Continuum chooses to represent itself to humans is that while the one Q we are most familiar with chose to wear the uniform of a Starfleet captain on a whim (to bother Picard, then updated it later on to bother Sisko), other Q's most often show up as a Starfleet captain despite having no real personal reason to, nor even a reasonable way to know how and that it got chosen, in the case of the imprisoned, suicidal Q.
The wormhole aliens in Star Trek: Deep Space Nine used the forms of the various cast-members when they manifested to Sisko. Once, Quark found a way of talking to them, and they got to use Sisko's form as well.
In the first episode they keep showing him the battle where his wife died, and one of the aliens takes her form. When Sisko angrily tells them he doesn't like this, she replies that "You exist here"—in other words, it's what they can get out of his mind because it's the thing he thinks about the most.
And the Caretaker in Voyager's pilot episode appears to the crew as a kindly old man in a holographic simulation of a Southern plantation, because it believed that would be a more comfortable venue than its true jellyfish-like form, briefly glimpsed at the end of the episode. Star Trek really did love this trope.
"Well! Since no one seems to care for any corn, we'll have to proceed ahead of schedule."
After Species 8472 took some mood stabilizers and stopped killing everything, they took human form to rehearse infiltrating the Federation headquarters on Earth. Later they have peace talks with Voyager, which would likely have been difficult in their original three meter tall form, where they kill everything they touch. Note that they were only killing everyone because they thought everyone was like the Borg, who tried to assimilate them.
The Changelings. Odo was essentially doing this every episode, which would actually make this the most frequent occurrence of this trope in the whole franchise. It was actually an instance of Character Development when he stopped being so compulsive about "A Form You Are Comfortable With" and became more interested in experiencing his own shapeshifter-hood, acquiring quarters and outfitting them with various objects to imitate, and "sleeping" anywhere he liked instead of in a bucket in his office. It was also provocative when he met Laas, another one of the Hundred changeling babies sent to explore the galaxy, and one who, bitter at the Solids, had no interest in making them "comfortable". But like the Q example above, all of the other changelings appear in a form resembling Odo's mostly-human-but-just-a-little-off appearance despite being capable of perfectly mimicking any species in the galaxy.
Note that the Changelings other than Odo seem to do it less to put the "solids" at ease and more to be able to be separate from them. Changeling infiltrators are shown to be able to mimic other people perfectly, but, because of their own sense of superiority, they seem to want to keep that separation in place when they are free to make the choice.
Lorien appears as a wizened old man-alien... but his true form is a starship-sized ball of tentaculared glowy gas...
The Vorlons — When Kosh saves Sheridan, he appears as whatever each person thinks an angel (or the equivalent) looks like, and he appears in Sheridan's and G'kar's fathers in their minds. It isn't until later, when Ulkesh (and the remaining fragment of Kosh hiding in Sheridan's body, which has apparently called Ulkesh out for a fight to the death) appears outside his encounter suit, that the true form of the Vorlons (thus far revealed only to Dr. Kyle and Lyta) appears: giant flying plasmatic squiddy things. Slightly subverted with the Shadows, who are frequently invisible but always corporeal and vaguely resemble giant spiky scorpions.
Londo claimed to see nothing when Kosh left his suit, with the implication that this was because he was touched by the Shadows. Word of God is that "Londo saw what he said he saw". It has been proposed by some that Londo saw nothing because he is an atheist, although his status as an atheist is only suggested in a conversation reported by Vir many years later.
Both the Vorlons and Shadows play the trope when they try to make one final push to woo the Younger Races in the Season 4 episode "Into The Fire". Sheridan, being convinced by the Vorlons, sees an Anthropomorphic Personification of justice encased in ice. Meanwhile, Delenn, being convinced by the Shadows, sees the people she's been most familiar during her time on B5, one by one, eventually seeing a duplicate of herself.
Both the Ancients and the Ori use this trope. The series even lampshades it stating that the Ancients used to be human-like beings anyway, so taking our form is as natural to them as breathing. If they still breathed, that is. Similarly to the Q Continuum example above, the plane of the Ancients is also presented in "A Form You Are Comfortable With" — as a homely American diner. Not just any diner, but one Daniel Jackson had gone to as a kid. Interestingly, Anubis appears as an overweight guy, which is definitely meant to trick Daniel, as Goa'uld always take beautiful hosts (his true form would be a small snake).
The Asgard, whom in their real shapes are typical grey aliens, have been impersonating the gods of the Norse pantheon by the way of holograms for millenia, until they deems the societies they protect are advanced enough to handle the truth.
The Gadmeer are a sulphur-based, reptile-like species that can't live in a regular nitrogen/oxigen atmosphere and have a very different set of senses compared to humanoids. So, to deal with the human-descended Enkarans and SG-1, their giant ship creates an android based on the appearance of an Enkaran.
Both types of Ancients in Farscape use this trope to appear to John Crichton: "Jack" of the Endangered Ancients typically appeared as Crichton's father, only manifesting his true insectoid form three times - including his death. On the other hand, Einstein of the interdimensional True Ancients chose the form of a well-dressed gentleman with pitch-black eyes.
In Joan of Arcadia, wherein God tells Joan directly, "I look and sound like this because this is what you can understand." Check the page quote for more.
Played straight and subverted with the First Evil. Able to take the form of any person who has died, the First sometimes will manipulate people by appearing as a comforting, departed loved one... but more often than not, it will maliciously choose whatever form will most freak its victim out. And it's really good at it, too.
Also Jasmine in Angel. She goes through great pains to manifest as a beautiful black woman in this plane, but her real form that can be glimpsed when she's feeding involves green light and tentacles. Also, anybody who comes in contact with her blood will see her as a rotting corpse.
Again used with Illyria who uses the general form of Fred (granted shes blue) despite the fact that it makes some people (especially Wesley) uncomfortable. Leads to a Major Tear Jerker in the final episode
Played with the Crossroads Demon, who almost always takes form of a sexually appealing woman. Considering that the demon seals her Faustian deals with a kiss, this probably plays into her advantage. Same goes for Lilith. Subverted in later episodes. The demons will appear in whatever body they've decided to possess, and they don't always pick a body just to seduce a human. Instead of a sexy lady or a young stud, Crowley (King of the Crossroads) possessed something along the lines of a well-heeled, middle-aged Englishman, which leaves one to wonder either a.) what advantages that meatsuit has other than appearance, or b.) if he knows something about humans that we don't (eg, we will do anything for Mark Sheppard).
In addition, angels have to possess human "vessels" in order to interact with humans, because seeing an angel's true form will burn out a person's eyes and its true voice causes shattered glass and bleeding ears. Castiel eventually reveals his true form is "about the size of your Chrysler Building." Which raises the question of why Lucifer and Michael even needed human vessels to begin with, since neither of them seem to care whether or not they harmed humans. Fighting each other in their true forms would have saved a lot of time and effort, as opposed to spending a season trying to coerce Sam and Dean into becoming their vessels. The only answer given so far is "Them's the rules." They're required to have a host, but we don't know why precisely.
This is also inverted with the Fallen Angel Anna, who takes a form she's comfortable with. She was a human, but became an angel again, which destroyed her human body. She decided that she liked that body, and "calls in some favors" to get it back.
Played straight in Dark Side of the Moon when the brothers visit Heaven. While there, the garden at the center of Heaven will change its appearance according to what the viewer most expects it to look like, becoming the botanical gardens in Cleveland for Sam and Dean. Also, angels still appear human and wingless, which is even lampshaded by Zachariah:
Zachariah: In Heaven I have six wings and four faces, one of which is a lion. You see this because you're... limited.
In later seasons after his angelhood is restored by God, Castiel has several conversations in Heaven with other angels, while no humans or other "limited" beings are around. They still appear as their human vessels.
Perhaps because the form of Heaven is established by the human souls within it, and the Angels live within whatever of these individual heavens they prefer. Castiel's favourite heaven is a beautiful garden created by an autistic man. Archangel Rafael's heaven is the office of a Corrupt Corporate Executive who repented.
Reapers also tend to appear in the form of a human to the recently deceased, such as Tessa appearing to Dean as an attractive young woman when her true form proved rather frightening to him.
Dean: You sure are a lot prettier than the last reaper I saw. Tessa: You saw my true form and flipped out. It kinda hurts a girl's feelings.
In a later episode, the ghost of a young boy was frightened of even Tessa's human form, until on Dean's advice, she changed her denim and leather outfit into a cute white dress.
In the '80s medical drama St. Elsewhere, Dr Fiscus (Howie Mandel) had an out of body experience while in surgery after an accident. During his ordeal, he meets God, who looks exactly like him. God's explanation: "I made you in my image, didn't I?"
Parodied in a Christmas special for Everybody Loves Raymond where Rob pretends to be Santa, but Ray's daughter isn't fooled. His response? He had taken the form of her uncle Rob because it's a form she'd be comfortable with. This is immediately Lampshaded by Ray, who says "You're Santa Claus, not a Klingon."
Done in the Animorphs live-action adaptation, where the Andalite Visser 3 takes the form of a human in order to make his enemies (humans who he thinks are Andalites) more comfortable. If you think that sounds like a poor excuse to cut corners on the show's special effects, congratulations, you're smarter than the target demographic.
Angels appear to characters throughout the series in the form of other characters. Notably Six to Baltar and vice versa, as well as an angel who looks like Leoben to Starbuck. Head-Leoben is the only one who confirms this, though. Head-Six and Head-Baltar appear in these forms even when no-one is around to see them. In fact, Tyrol implies that the Final Five designed Cylon Model Six after the angel they saw, not vice-versa.
That incident where Head-Baltar appeared to Baltar. Baltar was everything but comfortable.
The angelic-like ascended aliens (called Being's of Light)from the original series did this when they needed Apollo's help with a mercy mission. He got a sidekick that only he (and later Starbuck) could see called "John".
Sabrina the Teenage Witch makes a literal date with Destiny and he shows up in the form of a handsome young man. He says he could transform into the form with the flowing robes and white hair but most people tend to prefer the young man.
In LOST, the Man in Black/Smoke Monster can take the form of any person he wants, and he takes different forms to appeal to different people. To Jack, he was Christian; to Eko, he was Yemi; to Ben, he was Alex; to Richard, he was Isabella; and in his final form, when he intended to influence the island's entire population, he was John Locke. He could create hallucinations of almost anyone, but it’s implied that he could only physically mimic a limited number of people. Every solid human shape he takes is of a dead person whose corpse is on the island ("Isabella" never physically interacts with Richard). This would explain why he took the form of Christian in front of characters for whom that form carried no significance; Christian was the most convenient non-threatening form that he had in his repertoire at the time.
The Imagin in Kamen Rider Den-O have an intresting take on this trope. They ALWAYS take a form their host has knowledge of, as their form is from their memories. While this normally more comfortable than taking with a random floating orb of yellow energy with no face, it's different in that it's not for the host's benefit but because the Imagin wants a physical form.
Sarah: I guess I should've expected it. Neil: What? Sarah: God is an old white guy. Kurt: It's probably an artificial construct so we won't freak out, derived from TV transmissions. Sarah: How do you know that? Kurt: 300 hours of Star Trek.
Used in Power Rangers Megaforce, where mentor Gosei, an alien, admits quickly to the Rangers shortly after recruiting them that his appearance as a tiki-like face on the wall is merely one taken because its more comfortable for them than his true appearance, conveniently making him look similar to his mentor, Zordon, not that the Rangers could know it.
Depending on your interpretation of the Ashes to Ashesfinale, Nelson could be an Angel in Human form (supposing that Angels wouldn't look like humans to begin with),Jesus or God himself.
Subverted in a big way on Married... with Children where the Grim Reaper takes a form that Al is not comfortable with at all - Peg. And worse, while she does promise to spare him if his family admits that they need him, she cruelly mocks him the whole time, telling him about terrible fates waiting for him in the afterlife, then adding "maybe" to the end, just to keep him guessing. She does keep her word after Al wins the bet, but still manages to make one last jab before she leaves, saying she'll be back the day after he wins the lottery (adding "maybe" to the end once again).
In the episode "The Name of the Doctor," the Doctor admits that having travelled in time more than any other Time Lord in history, long-term exposure to the background radiation of the Time Vortex has rendered his "true form" as a Negative Space Wedgie woven within the fabric of the universe. This is revealed to be the "corpse" held within his tomb, rather than the actual physical body of his final incarnation.
The Doctor: What were you expecting, a body? Bodies are boring. I've had loads of them.
In the Doctor Who 50th anniversary special "The Day of the Doctor," the sentient superweapon known as the Moment appears as the Bad Wolf version of Rose Tyler, since it knows she is someone the Doctor trusted. Except he hasn't met her yet.
The Moment: She's from your past. Or was it your future? I always get those two mixed up.
This is why the TARDIS takes the form of a blue police box (or, in "The Doctor's Wife," a woman): to avoid blowing the minds of its passengers.
On Revolution, the nanites like to mimic the forms of people familiar to and loved by the person they're talking to, specifically because the person will pay attention and not freak out quite as bad (they do occasionally tend to think they're going crazy, though). They don't physically manifest, though; they simply alter the brain of the person to perceive them as being there - which tends to support the crazy theory, as others think they are Talking to Themself. Of course, since they're actually robots the size of viruses, seeing them at all would be quite difficult for a naked human eye.
Myths & Religion
This trope is at the least Older Than Feudalism, with gods taking forms that appeal to mortals, most notably Zeus. Indeed, the story of Semele has Zeus forced to show her his true form, which promptly kills her. And seeing as this is Zeus, he's got his reasons to make himself appeal to mortals.
Averted in Abrahamic religions. Seeing the face of God is said to result in instantaneous death. Moses, a favored prophet, was however treated to a view of the back of God. It sent him flying out of a temple and left his face glowing. The chariot of God, the Merkabah, is similarly unusual. Ezekiel and Isiah are great sources for descriptions of God as being difficult to describe. Also, these religions generally emphasize God having no physical form; it's considered fairly blasphemous to ascribe one to him. You'd have to ask a rabbi how someone could "see God's face/glory" then. Moses didn't even get to see the form of God, he was only allowed to see His radiance.
Additionally, angels tend to have disturbingly non-standard numbers of things like wings, eyes, and faces. It's telling about the "true form" of angels when, almost without exception, their first words are "Don't be afraid". Even the angels were described using this trope, since their descriptions don't normally work in the natural realm. Wings and wheels covered in eyes? They sometimes took on the appearance of humans, and they were still described as looking different.
The manifestation of God as a human in the form of Jesus is (or at least was 2000 years ago before people got used to it) playing the trope straight then, but subverting the expectations people had at the time.
The Tao te Ching is an attempt to do this to the Tao, through a series of analogies.
For the most part, the followers of Egyptian Mythology understood that the various forms ascribed to their various gods weren't supposed to be how the gods actually were. Those forms were supposed to be symbolic of concepts and traits found in the gods, with the actual gods themselves being thought to exist as abstract forces.
In Hinduism, this trope is sometimes performed trough the use of avatars. Most famously, Vishnu occasionally manifests on earth to communicate to mortals in human form. In the Bhagavad-Gita, Vishnu speaks to prince Arjuna trough his human avatar Lord Krishna. At one point, Arjuna asks if he can be allowed to see Krishna's true eternal divine form and the avatar agrees. He does first have to grant Arjura a divine sense however, since human eyes cannot see or comprehend the universal form of God.
Most Beholders are insane, convinced that they embody the perfection and any minuscule deviations from it should be exterminated, and thus (being an extremely flexible species) wage constant species-wide civil war. It's caused by their deity, "Great Mother" who also spawns different hive mothers in every clutch who in turn spawn different variant beholders. But how it's compatible with seeing Great Mother itself? Simple: every individual sees its own features (scaled up).
More literally, the very intelligent large or magically mighty beings in D&D, like dragons and deities, will often use their shape-changing abilities to become a human simply to make their human associates less freaked out (usually for the ulterior purpose of getting laid). It's where all the ridiculous half-whatever templates come from, and that dragons are the most common offender should be clear from the fact that a half-dragon race was added as a default player race in 4th edition.
In the few instances from Ravenloft history when the Dark Powers have contacted someone, they've done so with an audio-only inversion of this trope: taunting, tempting and tormenting a nascent darklord using the voices of said darklord-to-be's friends, family, and enemies. In short, A Voice You Are Uncomfortable With.
The Emperor of Warhammer 40,000 did this as a matter of necessity, appearing as (very) large human wearing armour because his true form would also expose any viewers to his psychic presence, which even ten thousand years after his apparent death is powerful enough to burn out the eyes of anyone who makes even momentary psychic contact with him and is capable of maintaining a galactic navigation beacon. Sort of. He actually IS a giant man in stupendously ornate armor. Whether he grew into gianthood or performed genetic experimentation on himself is never stated. What he actually masks is his psychic power, not his body. Baseline humans that see him are dazzled by a blinding light about one notch down from a Beatific Vision. Psykers get a wonderful dose of Your Head Asplode. Then he starts actually doing things and it makes sense why he's referred to later on as the God Emperor.
The Unconquered Sun has appeared in the form of a handsome four-armed human since the time when humans became the dominant race of Creation. Prior to that, he appeared as a golden scaled humanoid tyrannosaurus in honor of the Dragon Kings, who were his most ardent worshipers. He's also capable of assuming practically any form if he wants to make himself more (or less) comforting to another. His reason for assuming other forms is partially as an expression of respect and solidarity, partially for the sake of being comforting and partially because his true form (a humanoid figure of molten gold and obsidian studded with galaxies, with blazing eyes and countless arms) would burn out the senses of practically any being that viewed it.
Other Incarnae also have the power to assume more comforting forms. Luna in particular is defined by being a shapeshifter, with a multitude of forms and identities, some of which are specifically assumed to be comforting to others.
There's also the implication that some of the jouten (bodies) of certain Primordials serve the purpose of giving them a means of interacting with lesser beings in a context other than complete awe and terror. In most cases, this doesn't constitute actual shapeshifting; they're just capable of existing as multiple bodies simultaneously.
Nyarlathotep, alone among the Outer Gods, cares enough to manifest in an appearance that won't drive human beings insane. Ultimately subverted, as this is just a subtler way for him to spread madness and destruction.
Nodens and Hypnos also exhibit this trope, albeit for very different reasons.
In Marlowe's Doctor Faustus, the eponymous scholar is appalled by the first form Mephistophilis presents himself in after being summoned (it's never made explicit in the text what that form resembles), and asks him to come back in the shape of a Franciscan Friar.
The alien conqueror Jenova from Final Fantasy VII. Her original form is that of a naked woman, though it's not a very convincing disguise: she's missing arms and feet, is surrounded by fleshy tubules (or, in the updated Crisis Core version, a giant heart) and monstrous wings, and Jenova was apparently fuzzy on where eyes are supposed to go. However, it was enough to lure the Cetra to their doom. Jenova's been locked in this form ever since she was mummified and placed in cold storage by Shina Inc. Upon reawakening, she spends much of the game disguised as Sephiroth, who - in a role reversal - is frozen solid and requires Jenova to come free him.
In Persona 4, Teddie, a Shadow, does this unconsciously so as to appear nonthreatening to the humans he wants to become like. Also, Izanami as the gas station attendant, and when she reveals herself for what she is. She just appears as a young woman wearing a shimenawa mask, whereas her true form is most likely the rotting mess from mythology.
Alex Mercer and Elizabeth Greene, from Prototype, look human enough to begin with, albeit able to shapeshift and turn parts of their bodies into weapons. Eventually, though, you realize that the human form of Alex is just like all of his other disguises and that he is really the Blacklight Virus, released at Penn Station by the real Alex Mercer; before that, "he" just looked like thick, bright red goop in a test tube. Later in the game, Elizabeth Green turns into a mountain of flesh and biomass growing out of the sewer at Times Square, giving you a hint of how Alex might truly look. Subverted by the fact that Alex himself genuinely believes he is his human form, at least until someone tells him otherwise.
A rare example of this being played for horror comes in Project Origin with Alma. She pins Beckett to a wall, looming over him looking like an emaciated corpse, but then retreats and takes on the form of a healthy, attractive young woman. Made horrifying by the fact that Alma is in love with Beckett, and it's quite clear that she's doing this to appeal to him.
The main characters of the Mega Man ZX series have to do this. If you attempt to talk to civilians while not using their human forms, the civilians flip out. The official explanation for this is that they're afraid of you, but this hardly seems to hold for those who tell you that to talk to them, you need to "ditch the crazy outfit". The human form is also the only form that doesn't aggro city guards.
All powerful dragons have the ability to take on a human(oid) form whenever they want. Some even adopt aliases and pass themselves off as (relatively) normal people to suit their purposes (be they good or evil). That said, the method of getting aliases and infiltrating mortal societies has become so well-known that Genre Savvy people can spot a dragon-in-mortal-form from a mile away. In response, some dragons have stopped bothering with perfect disguises and let some of their draconic featured remain visible, thus increasingly subverting this trope. Most dragons prefer to take elven forms, as they believe humans to be inferior creatures. Even Korialstrasz/Krasus, who is pretty friendly to humans, takes the form of an elderly elven mage. Deathwing and his ilk only take human forms in order to infiltrate the human society. Other dragons occasionally appear as other races, such as goblins, but only when they're undercover. Chronormu/Chromie seems to be the only dragon who preferentially adopts a gnome as their mortal form because it suits his/her personality.
The ethereals also invoke this trope. Beings of pure energy in their normal form, they take a more approachable guise when trading with mortal races.
The various dragon gods in Breath of Fire IV each possess two different forms, a giant, monstrous form they take when summoned and a smaller humanoid form they take when conversing with the party. During the party's first meeting with Pung Ryong, the wind dragon, he comments "perhaps this form will be easier on your eyes" as his humanoid form appears.
Male Morrigi in Sword of the Stars. Being powerful psychic beings, they automatically give off a psychic aura that makes anyone looking at them see a divine, "good" creature from their own mythology instead of their true forms (as an example, most humans see angels). Since the Morrigi are traders and diplomats by nature, this tends to smooth over diplomatic functions with other species quite nicely. Interestingly, this aura is primarily meant to attract females, similar to the tail feathers of male peacocks. Morrigi females look for a male with the most beautiful (i.e. strongest) aura, while Morrigi males look for a female who can resist their aura.
Subverted in The World Ends with You with Joshua, because downtuning his vibe automatically gave him a human appearance. Played more straight with the Reapers, who appear in the Realground without their bat like wings.
In the God Game Black & White (specifically, the first one), the mortal villagers of Eden only see You as a rotating ball of energy with a symbol on it. As the player, You see a hand... one that that reflects everything You've done on Eden. As the developers wrote in the making-of book, there are no mirrors on Eden.
Implied to be the case with the shapeshifting Flemeth in the Dragon Age franchise. In the first game, she presents herself as a ragged old woman, and only goes One-Winged Angel if forced. In the second, when rescuing the Hawke family from darkspawn, she starts out in her dragon form and then shifts to a white-haired valkyrie look. She notes how "bodies are such limiting things" and alludes to the fact that she's much more than a "simple" Monster Lord. What she is exactly remains a major mystery of the series.
Hawke: Impressive! Where'd did you learn to turn into a Dragon? Flemeth: (Laughs) Perhaps I am a Dragon?
In Mass Effect 3, the Catalyst appears as the little boy who was killed at the beginning of the game.
When Shepard enters the geth consensus to remove the Reaper Code infecting the system, Legion installs sensory filters so that an organic can make some limited sense from a virtual world designed for synthetics. The debugging software takes the form of a giant gun. When asked about it, Legion clarifies that the geth chose something familar for their benefit, which Shepard takes as a backhanded compliment.
In the Leviathan DLC [[spoiler: the actual Leviathans resemble the Reapers (since the first Reaper was created from them,) but when telepathically communicating with Shepard they do it via a continuously changing vision of various people they have met. As the Leviathans are merciless and believe themselves akin to gods as much the Reapers do, including brainwashing and killing many people to prevent their discovery, it is unlikely they were doing this for Shepard's comfort, since the mental link causes Shepard to suffer a nosebleed.
Played with in Catherine. Catherine is a succubus, meaning that she changes appearance playing up to the fetishes of the men she seduces prefer. You only see one form during the game, but we possibly see her true form in the True Cheater Ending.
Final Fantasy X: The aeons have two forms, their original human form for talking with summoners and their guardians and their spiritual form for fighting.
Implied in FTL: Faster Than Light. The Engi are beings composed of lots of nanomachines. They usually have a humanoid shape, but one event describes some Engi becoming vortices to work on special machines.
Used with terrifying effectiveness in Off, in The Judge's ending, wherein The Batter suddenly changes forms to become a Humanoid Abomination. However, this can be considered as an Epileptic Tree, due to the fact that we don't know if he suddenly changed, or if he looked like that the whole time.
Subverted in Pokémon Mystery Dungeon: Gates to Infinity. The Voice of Life, the embodiment of the world's will to survive, has chosen you to help combat the forces that seek the world's demise. To do so, it takes the form of Hydreigon, a three-headed dark-type dragon with pupilless red eyes that even the Pokédex refers to as "the brutal Pokémon". It's more of a meta example, however, as the only Pokemon in the story who actually seems to be bothered by his appearance at one point is Dunsparce, who isn't exactly brave. The fact that he introduces himself as Hydreigon seems to imply that he might not have any choice in the form he takes, either.
Played with in Saya no Uta: Saya appears to Fuminori as a cute girl not because she's changed her form, but because Fuminori's altered perception makes her look that way to him; as a result, he's the only person who doesn't go insane just by looking at her.
Higurashi no Naku Koro ni subverts this heavily with Hanyuu. While the basic objective is the same (bonding with Rika better) her true form is actually just 10-12 years older than the one she uses.
In Red vs. Blue, when speaking with Caboose, Epsilon (or, rather, the memories of other AI fragments within Epsilon takes the form of Delta, who he knows Caboose was comfortable with. He explains he isn't really Delta, but considering Caboose's mental state, he probably didn't fully understand that.
Something does this by accident in Beyond Reality. It's trying to not appear as something the human is comfortable with, but doesn't know much about humans, and thus has to make an educated guess.
Interdimensional Being: You... don't find it frightening? Orion: Um... well, why a fish? It's not even a particularly freaky fish. Interdimensional Being: Fish are scary! Orion: You're scared of fish? Interdimensional Being: No! It's just... dammit, I'm an interdimensional being. Do you know how tough it is to tailor your intimidation to billions of different cultures? 98% of sentient beings in the multiverse find fish terrifying. How was I to know you came from the other 2%?
The insectoid Princess Voluptua in The Inexplicable Adventures of Bob! usually interacts with Earthlings by disguising herself as a beautiful woman. One of her subordinates criticizes her that "'Tis undignified for the heir apparent to dress like a monkey!"
Played for laughs when Blade Bunny expresses disgust for being stared at by a big gooey dragon's eyeball that is bigger than she is. The dragon then voluntarily shrinks down small enough... for Bunny to punch out.
In El Goonish Shive, Chaos seems to be trying to invert this trope by appearing as a little girl. What she says and does is more creepy that way. Also played straight later as she takes the form of Fox, Nanase's summon, to wake her up and get Nanase to listen to her so Nanase will do what Chaos asks with out freaking out too much. Nanase eventually catches on that she's not Fox but by that time she doesn't care and is willing to do what Chaos asked anyway.
In Wayrift, the Arweinydd Zemi Dreigiau appears to people in person form or dragon form — depending on his mood. The Arweinydd Zazo also takes on a wolf form to communicate with people, and eventually takes the form of a woman to gain attention from the man she's in love with.
In Erfworld, the mysterious Charlie assumes a variety of different forms whenever he psychically communicates with someone. To the reader, they come off as fourth-wall-shattering references, but given that almost everything in Erfworld is a warped version of Earth pop culture to begin with....
Played with, parodied, and inverted in one of the PvP Halloween storylines, in which Brent was abducted by aliens. They first appeared as tentacled slime-blobs, wearing plastic superhero masks in order to blend in. Once they'd kidnapped Brent and were trying to speak with him, they revealed that this form was an attempt to appear pleasing to Earthlings. It didn't work, so they tried option #2: Alf. (This just made Brent scream louder.) Finally, they dropped the disguises and appeared in their true, horrifying visages: cuddly hamster-creatures similar to Hamtaro.
Alien commander: Have everyone in research killed.
In The 10 Doctors, the Guardians say that their appearances change with the needs of their desired champions. In the story proper, they manifest as attractive humanoid women in order to toy with the Tenth Doctor's need fo meaningful companionship, and in a flashback, the White Guardian manifests to Davros as a military officer.
In All Night Laundrythe TV monster apparently. We're not sure what it is exactly, but Bina seems to be the only one who sees it as a TV.
On the final episode of Cracked TV, Clippy (after going insane and trying to take over the show) appears before Michael — played by the exact same actor with a sombrero, a fake moustache and a bad Mexican accent.
Michael: Clippy. You're taller than I expected. Clippy: I have chosen the form that is most pleasing to you. Michael:(beat) Is that a gay joke? Clippy: Eh. More a narcissism joke. Plus, this is the easiest way to shoot the finale.
All of the Anthropomorphic Personifications in the Global Guardians PBEM Universe are made of this trope because, being the physical incarnations of ideas, everyone has a different interpretation of that idea. What this means is that two people could be talking to The King (the Anthropomorphic Personification of "The Legend of Elvis Presley") and he'd look precisely like how they think Elvis Presley looks like when they think of Elvis Presley (meaning if one person pictures Ed Sullivan-era Elvis, he looks like Ed Sullivan-era Elvis; if they picture Vegas-era white-tassle pudgy Elvis, he looks like Vegas-era white-tassle pudgy Elvis).
Kaja of AJCO is normally quite human in appearance, despite the wings and halo, solely to make sure humans like and trust her. Get her angry enough, however, and she'll drop the act. It's pretty horrifiying.
On deviantART there is this prose piece called "God Drinks Black Coffee". The main character meets God on the sidewalk in the form of a woman.
An alien takes the form of Dr. Venture's father. Venture then calls the alien out for doing so because it brought up a lot of painful memories, so the alien reveals its true form and freaks out everyone present.
Possibly parodied/subverted with The Master, Dr. Orpheus's teacher. We've never seen his true form, so we have no idea is he's human, or what. But instead of taking on forms to comfort people, he seems to choose ones to screw with their heads (or at least to engage in Power Perversion Potential) though he always claims there's a valuable lesson in them.
Lampshaded and Double Subverted in Cancelled. The alien initially takes the form of Stan's father and the kids first think that the whole "alien taking a form you are comfortable with" trope is lame. But when the alien then takes its true form, they scream and quickly ask it to go back to a "comfortable" form. They then spend quite a while going through possible forms (including Santa Claus, Saddam Hussein, and Missy Elliot) until they arrived at a taco that craps ice cream.
The form of Moses in the Super Friends episode — a giant spinning orange energy prism! Yeah. Not just any spinning energy prism, but a carbon copy of the Master Control Program.
Dib: Who—what are you, and why did you transform into giant shoes?! Meekrob: We are beings of pure energy. This is merely a form your human brain can understand. Dib: But—you just looked like aliens before you turned into shoes. Meekrob: Hmm... yes. But you couldn't comprehend that. Dib: Yes I could. (the lead Meekrob slaps him with a shoelace)
First, in "The Last Temptation of Homer", Homer's guardian angel appears to him in the form of Sir Isaac Newton, "a man you would respect and admire." When he realizes Homer has no idea who Newton is, he instead takes the form of Colonel Klink — which he reallydidn't want to do.
In "Hungry, Hungry Homer", when Homer loses faith in his hunger strike, he is visited by the ghost of Cesar Chavez — who appears in the form of Cesar Romero, since Homer doesn't know what Cesar Chavez looks like.
Steve: Wow! Angelina Jolie! I have so many questions to ask you. Is that whole thing about you sleeping with knives in the bed true? God: I'm not Angelina Jolie, Steve. I'm God. I simply chose the form most pleasing to you. Steve: Oh, you're God. ...So is that thing about Angelina Jolie sleeping with knives in the bed true? God: Yeah. It's messed up, isn't it?
Oddly, He later appears again as a typical Grandpa God in Heaven. Well, that's how he appeared to Stan, who's something of a Christian fundamentalist, so Grandpa God is probably the only form Stan is willing to accept.
When the Vok talk with Optimus Primal in Beast Wars, they take the form of the head of Unicron, having scanned his mind and determining it to be a "figure of authority" that Optimus would listen to, though it was more likely "A Form You'd Know Not To Screw With". Pulling such a stunt is entirely in character for the Vok. They do show their true form to Tarantulas, when he tries to mess with their Tigerhawk puppet. He freaks out and tries to kill them with a big laser, only to get himself killed. Here is their true form◊.
Star Trek: The Animated Series episode "The Magicks of Megas-Tu". The inhabitants of Megas-Tu do this for their own bodies and their planet's surface so the crew of the Enterprise can comprehend them. Lucien turns the planetary surface to a forest glade, and the other Megans change it to a recreation of Salem, Massachusetts during the Witch Trials.
Daria. Daria met many holidays at the "Depth takes a holiday" episode. Christmas, Halloween and Guy Fawkes day wanted to start a band, but Cupid and Saint Patrick day wanted them to return home. They are supposed to say that home is "in your hearth", but it was actually in another dimension they could access through a dimensional wormhole at the back of the Chinese food restaurant. The holidays seem and act like common teenagers, and in their dimension they are all at a place that seems like Lawndale High, but which is worse (a quote that Daria and Jane will be repeating in their adult life).
In Young Justice, Miss Martian is a White Martian. Since White Martians are pretty hideous by human standards she uses her shapeshifting powers to look like an attractive young green-skinned humanoid. She based her humanoid form along with her entire personality on broadcasts of an old television show "Hello Megan!" since she hated her lonely life on Mars. As far as she is concerned, her "disguise" is her true self, so this is actually more a case of a form she is comfortable with.
Definitely the case of the shape-changer being the more comfortable one. While the Team is momentarily creeped out by the revelation, they get over it quickly.
Kaldur'ahm: Did you really think we would be so shallow?
In both Avatar: The Last Airbender and its Sequel SeriesThe Legend of Korra, the Avatar spirit takes human form to learn more about the humans it has chosen to protect. Most of the spirits either play this straight or invert this, as their usual form tends to be something like pandas, giant wolves, or owls, but they're capable of looking like an Eldritch Abomination when angered. It's unknown which they prefer.
Some zoos have been known to feed animals using hand puppets that look like an adult of that species.
This is actually necessary for baby primates when humans are feeding them. The human wears a monkey suit to simulate the fur of the mom. This way the baby will accept the mother when he's returned to her.
It's also necessary for avians. Birds that "imprint" on humans when they are infants will think that humans are like them, or that they are like humans. This can lead to difficulties, if the bird in question is a part of a breeding program to keep the species from dying out. Ducks and geese are best known for this problem, and may actually end up not knowing how to fly (since humans don't). This is referenced in the Discworld novel Guards! Guards!, in which a human raised by dwarves is likened to a duck raised by chickens.
Worse, a hawk or owl who is imprinted on humans may not be able to hunt and would fly to humans it found once released in the wild, hoping for food. A raptor imprint can end up a permanent captivity resident.
The most famous phenomenon this leads to is talking birds; for a parrot to be ready to learn to talk, it has to be separated from any other parrot, so that it imprints on its human owner and tries to imitate it.
Some Chinese zoos have had their zookeepers dress up like pandas when taking care of baby pandas in the zoo. The logic behind this is that the baby pandas won't form human attachment so that they can be released into to wild later on.
Quantum mechanics can be a bit like this. One example is the quadrupolar echo pulse sequence in nuclear magnetic resonance spectroscopy. The math works out perfectly, but trying to visualize it invariably winds up with the spin pointing 90 degrees from where the math says it should be and where experiment confirms that it actually is. The lesson here is that once you get deep enough, physics really is just math, and what you think of as "physics" is just a Form You Are Comfortable With.
Computer interfaces. Raw binary data is near-impossible to process for humans, and the inner workings of software are not only difficult to understand, but aren't of interest to most users. User interface is an abstraction that presents only the data the user wants, and in an easily understood form at that. Even most programmers deal with high-level programming languages and platforms that abstract away many layers of complexity irrelevant to the task.
A less extreme version of this trope would be "a form you will find more useful", and is practically ubiquitous with diagrams and route maps. If you're trying to find your way around a metro system, or build a complicated electrical circuit, a simplified not-to-scale representation using accepted symbols will be much more helpful than a completely accurate photorealistic image of the system.
By extension, pretty much all metaphors, allegories or symbolism could be said to be aspects of this trope.