Hellish Pupils



"Cuchulainn has FOURTEEN FINGERS AND FOURTEEN TOES ALSO FOURTEEN PUPILS WHY FOURTEEN PUPILS? BECAUSE TWO PUPILS IS NOT ENOUGH TO WITNESS THE SHEER QUANTITY OF HOMICIDE HE COMMITS"

- Cuchulainn is a megatron of killing people, Bettermyths.com

A character's pupils are slitted like a cat's or snake's, or rectangular like a sheep's or goat's, to indicate that they're channeling something nasty (or that they are nasty, period). Often with a red or yellow eye color to accentuate the wrongness. Also eyes have such unusual designs that they seem wrong in the worst way.

Curiously, nobody ever seems to notice this if the character isn't a known antagonist. It's a Red Right Hand to identify trouble to the audience.

Sometimes this is the Glowing Eyes of Doom with the dimmer switch turned down.

A subtrope of Technicolor Eyes and Uh-Oh Eyes. Not to be confused with evil schoolchildren.

Compare Fireball Eyeballs.

Anime and Manga

 * Sumire from Venus Versus Virus has cross-shaped pupils along with Red Eyes, Take Warning while in her Berseker state.
 * Xellos the Priest of Slayers has these, along with purple eyes. Naturally, they serve as a Red Right Hand to his true nature as a Monster, and he only shows them when he's being serious. Normally, he has Eyes Always Shut.
 * Used by Evangeline A.K. McDowell of Mahou Sensei Negima whenever she taps into her vampiric powers: the pupils slit, the sclera turns black and the iris starts to glow yellow. Interestingly enough she only does this AFTER she relinquishes her antagonistic role, for such purposes as scaring the shit out of Anya for the lulz.
 * Used by certain of the Aoyama girls in Love Hina, typically right before doing something violent/evil. Happens somewhere around Chapter 70.
 * Many of the Homunculi from Fullmetal Alchemist.
 * In fact, you can note the contrast between human eyes and homunculus eyes in the first anime when
 * Kimblee, who is human but a complete psycho has creepy, reptilian eyes.
 * King Bradley has his  on his left eye, covered by an eyepatch.
 * Ichigo Kurosaki from Bleach does this whenever his inner Hollow is about to take over, changing the color of his irises to yellow, and the color of his eyeballs to black, with a half mask to boot. Later in the series,.
 * Ulquiorra Cifer's pupils are slitted. When he, his pupils are still slitted.
 * Gajeel Redfox from Fairy Tail has slitted red eyes, like those of a lizard or dragon. Makes sense, since he's the Iron Dragon Slayer, was raised by a dragon, and is easily the most feral of the seven Dragon Slayers shown so far.
 * The Raijinshuu, Evergreen and Bickslow eyes glow underneath their Power Limiter, while Fried on the other hand has sclera turns black with a glowing purple pupil.
 * Kirika's eyes in Noir become blank and soulless slits when her "other" personality awakens.
 * In this case, her partner Mireille very clearly notices that something is wrong, making her more attentive that most people in animeland.
 * Chloe has similar, if only slightly softer eyes all the time, indicating how she is far more deeply and closely indoctrinated to her role as Noir, than either Kirika or Mireille.
 * Prince Lotor from Voltron.
 * Nehellenia from Sailor Moon.
 * The half-yoma fighters in Claymore have eyes that are normally silver—these turn into gold eyes with slitted pupils once they start to tap into their yoma power.
 * If someone's eyes do this in Higurashi no Naku Koro ni, they're in big, big trouble.
 * If someone's eyes lack pupils, that's a sure sign of craziness or emotional brokeness.
 * Tyranno Hassleberry/Kenzan from Yu-Gi-Oh GX gets Hellish Pupils whenever accessing the power of his "Dinosaur DNA" that he gained from a bone transplant from an accident at a fossil dig.
 * Then when Judai enters Haou mode or becomes Haou Judai, his eyes turn an evil yellow. After  they then turn green and yellow, same as
 * This is also one of the defining traits of the Dark Signers—they have very small pupils as well as black sclera.
 * Around half the characters in Gundam Seed, and almost any other show involving otherwise Badass Normals with some form of berserker ability.
 * Vinegar Doppio gains nightmarish black pupils with smaller black dots around them whenever
 * Ayano, in Kaze no Stigma.
 * Several different characters in GetBackers begin to reveal that they carry towards the end of the manga. Generally, characters use special contact lenses to hide this trait. When they remove the lens, however, even running away is generally not going to do much good. Other characters don't bother to hide it at all. Taken to its extreme by.
 * Train Heartnet from Black Cat sports a cat's slit eyes, although it seems to highlight his feline features more than it makes him evil. When the slits become especially pronounced, however, bad things start to happen. He manages to scare an entire squad of bodyguards into submission just by walking past them with these eyes.
 * Which makes them among the most Genre Savvy Mooks in any manga in history.
 * Whenever Naruto begins using the Nine Tailed Fox's power, his eyes turn red and his pupils become slits.
 * Additionally, when Gaara's demonic side comes out, his eyes turn yellow, with pupils shaped similarly to those of the image above those of the image that used to be this page's picture over a year ago, along with the sand that envelops his body.
 * And let's not forget the Sharingan eyes, which are possessed by Sasuke, Itachi, Kakashi and various other characters.
 * And Naruto again, when he completes the Sage mode, accompanied by "froggy" eyes with rectangular pupils.
 * Additionally: at one point, he uses both sage mode and fox chakra at once, and both kinds overlap with each other. Like this: +_+
 * Naruto has plenty of these, with the Rinnegan, Orochimaru's eyes... actually, most of the Akatsuki seems to have strange eyes.
 * Kyo from Fruits Basket is possessed by the Cat spirit of the Zodiac; thus, when he's angry or otherwise extremely emotional, his eyes become yellow and slitted. Played almost always for comedy in the anime, but the manga uses it half the time for dramatic effect.
 * In the manga, Yuki has a similar effect; on occasion, he's displayed something like the Rat's eyes, where his eyes lighten and his pupils disappear altogether.
 * On the other hand, Hatsuharu, when he goes Black Haru, goes from this to this. Akito has done this too. Basically, if Natsuki Takaya draws someone's pupils clearly defined, then something's going down...
 * Only sort of an example (as the character is clearly not human), but Ryuk from Death Note has red pupils. (Another shinigami, Rem, has the classic gold-eyes-slit-pupils.) A clearer example is any character who makes the shinigami eyes trade, who have demonic red pupils.
 * Another not-really-human example: Arcueid from Tsukihime. Whenever she gets really, really angry, her Mind Control Eyes turn Gold and slitted, at which point only the strongest of characters can fight back, or even move.
 * The Blade Children in Spiral all have slit pupils (and crazy hair colours). They don't seem to actually exist, as the characters constantly talk about how the only way to identify one is their missing rib.
 * This is kind of weird, actually. With the five primary Blade Children, the boys always have the slit-pupils, while the girls only have them when they're feeling something very strongly. The anime uses this to good effect in one episode focusing on Sayoko Shiranagatani, a Blade Child who has amnesia and is being targeted by a Hunter. The camera constantly focuses on her eyes when she's in danger, and her pupils never go down to slits the way Rio's or Ryoko's would, emphasizing the point that she's escaped the Blade Children's fate.
 * Or the fact that she's completely deadpan and emotionless in that episode. Anyway, the above only works with the anime; in the manga, Blade Children's pupils go weird when they're feeling murderous - either actually fighting or just being threatening. (It makes the threatening very effective.) That also stands for the boys and is particularly striking in Kanone's case, as his eyes go from large and kind-looking to just freaky.
 * And then Hizumi's eyes are just crazy all the time. (It's in fact sort of related.)
 * Alucard of Hellsing manifests slitted, cat-like pupils when using his Mind Control Eyes in the manga. Recent chapters have shown Integra Hellsing's eyes like this in some panels, though whether this is a side-effect of keeping a fully powered Alucard under control or just a sign of being extremely pissed off is not addressed.
 * In Tengen Toppa Gurren Lagann, Nia's cross-pupiled green-and-pink eyes are pretty freaky when you first see them, but still extremely cute.
 * Viral also has Hellish Pupils, and he's a particularly Badass Longcoat in a series that runneth over with Badass.
 * Justified Trope in that he's part cat-shark-man, so he has cat-like pupils.
 * Lord Genome has spiral-shaped eyes, but this is less to show him as being evil (since he's a Well-Intentioned Extremist) and more to emphasise his Badassery and mastery of Spiral Energy.
 * When the not-quite-a-vampire Arystar Krory in D Gray Man drinks the blood of an Akuma, his hair stands up and his eyes get this black veiny sunken look to them. He is a good guy, though.
 * Let's not forget Allen Walker's cursed eye, which goes black with concentric red rings when he spots an Akuma.
 * Rosario + Vampire has Kiria. Bonus for them being Mismatched Eyes Hellish Pupils, specifically one vertical slit, one horizontal.
 * Karin, a Friendly Neighborhood Vampire from Karin (aka: Chibi-Vampire), usually has normal eyes. Whenever she gets stressed out, her pupils remain circles but also gain vertical slashes—a merge of human and catlike pupils in one package. Her eyes also apparently turn gold.
 * Nearly all of the hommunculi of Busou Renkin display these, as do their human followers. When she's angry, the heroine, Tokiko also displays them.
 * The Black Cloaked cultists in Mai-Otome get gold cat's eyes when they draw upon the power of the Slaves.
 * All of the demons in Chrono Crusade have these (of course), but some are more evil than others—in fact, the title character (Chrono) has them, and he's one of the good guys.
 * Rokudou Mukuro of Katekyo Hitman Reborn has a red eye whose pupil is actually kanji that cycle from one to six, from the six realms concept in Buddhism. Each kanji represents a power derived from one of the realms...yes, including Hell. However, the one Mukuro believes to be the worst is the fifth realm, the one of humans.
 * Bardiche of Magical Girl Lyrical Nanoha used to have a slitted eye in its Power Crystal. When Fate switched sides, the eye is never seen again.
 * In Hayate the Combat Butler Manga only, Hinagiku and Wataru. It might symbolize their aggressive personalities; as they're certainly not evil. Certain other characters get them when being sneaky/violent, but these two sometimes have them when not doing anything in particular. There is no meaning, yet. In the anime adaptation, the Superintendent and Wataru normally have the eyes, and Hinagiku can summon it when she gets really annoyed.
 * In Soul Eater Arachne has spiderweb patterns on her eyeballs; Medusa (shown above) has snake-like eyes; Asura has 'eyes' inside his eyes (more like vertical eye-shaped irises).
 * Not to mention when  starts showing signs of turning out like   his pupils sometimes have yellow stars appear in them.
 * This is also inverted somewhat since some normal characters have strange pupils (for example Kid has multi-shaded gold coloured irises while Maka's aren't even visible unless she's getting worked up).
 * Kid's eyes can look kind of creepy. Can't see another example of it, though, so might be a one-off. In his case, the main physical indication he's other than human has turned out to be his hair.
 * Another slightly off indication would be whenever his eyes are drawn triangular and blank white. This has shown up in two particularly intense/serious fight scenes - when he's forced to fight both Black Star and later Mosquito 'seriously'.
 * Blair's human form features yellow irises and slitted pupils, akin to Medusa. Justified that she's actually a cat.
 * Outright subverted in The Law of Ueki by the title character Kosuke Ueki, who has very narrow slit-like irises (possibly just pupils and no irises at all), and yet he's a very kind and just person. The same is true for his mentor Kobayashi... when his Scary Shiny Glasses aren't in full swing, that is.
 * Ge Ge Ge no Kitaro has this in spades because let's face it, it's full of fucking youkai.
 * Yomi of Ga-Rei. It's much clearer in the prequel anime, Ga Rei Zero. Either way, she's more of an Anti-Villain than anything else.
 * A subversion of this can be found in Natsume Yuujinchou, where the protagonist has slitted eyes, but this indicates not that he's a nasty youkai but that he can see them. Played straight with some youkai, who also have slitted eyes and at least start off rather nasty.
 * Kisara in Kenichi: The Mightiest Disciple has catlike eyes. Initially this depicts her as vicious, but a new light gets thrown on this with the discovery that she is actually a closet Kindhearted Cat Lover.
 * Aagard Jum Sai, the Muay Thai master of Yami, has asterisk-shaped pupils. I'm not sure how that works either.
 * Subverted with Fujimaru and his dad, whose Hellish Pupils show up when they're about to do something heroically badass.
 * Subverted/played as a variant of Mystic Eyes in the manga adaptation of Breath of Fire IV. In this 'verse, Hellish Pupils are seen as Dragon Eyes, signs that the bearer is of great destiny and possessed with Psychic Powers of Precognition and Clairvoyance . (This even extends to a summoner-character developing Hellish Pupils when voluntarily possessed by Cool Big Sis Deis.)
 * Charlotte, also known as Lotti, of Pandora Hearts. Also Zwei and.
 * has them too.
 * Dunno if it goes here or not, but the Vestals from the New Vestroia Season of Bakugan Battle Brawlers don't have black pupils. Instead, their pupils are simply a darker shade of their iris color. They also lack the shiny glint that human eyes have. Not Mind Control Eyes in that it's a racial feature that even the good guys have and everyone is acting autonomously. They also fall under the Technicolor Eyes category.
 * Andrea of Gankutsuou has these, which help to highlight his insanity.
 * Luka of Uragiri wa Boku no Namae wo Shitteiru.
 * Digimon Tamers has Guilmon do this whenever he smells a Digimon. His normally round pupils go slitted and he starts growling.
 * Inu Yasha is a half-demon White-Haired Pretty Boy that has Eyes of Gold with slitted pupils. Considering what those tropes usually represent it is a little surprising that not only is he a good guy he's the hero. His brother, Sesshomaru, has them too.
 * Now, if his pupils turn slitted and blue, then we have a problem.
 * In fact, this trope makes his transformation a double whammy; his sclera also turn red.
 * The same applies to Sesshomaru. (This also gives a really good excuse to flee; you don't want to mess with an unbelievably large, powerful, angry, and regally fluffy dog demon lord.)
 * Many, if not most, bestial Youkai also have slitted eyes. And yes, that includes Shippo and Kirara / Kilala.
 * In Kuroshitsuji, when Sebastian is acting especially demonic, his eyes are a dark shade if pink and his pupils are slits
 * Also, In episode 12 of Season 2
 * Cell from Dragon Ball Z has these in his first form.
 * All Dream Demons in Yumekui Merry have eyes with pupils of nonstandard shape, which occasionally glow white. Merry herself has rectangular pupils like a sheep's.
 * In Sugar Dark, the main character/prisoner/forced grave digger/former private Reed meets Raven, a young mischievous boy who was among the mysterious masked people who ordered him to bury one of the Eldritch Abominations and humanity's ancient enemy called the "Dark" http://www.mangafox.com/manga/sugar_dark/c002/26.html. He doesn't appear to notice (or perhaps not to further question - what with shit happening to him in such short intervals) that he has http://www.mangafox.com/manga/sugar_dark/c003/20.html goat's eyes.
 * Used occasionally in Wandering Son, typically for Anna or Riku (both characters have Tsurime Eyes), but not in a negative manner. It's just used as a cartoonish effect.
 * Berserk: Guts gets these when he's in his standard action kill-kill-kill mode, which are merely his irises drawn in scribbled detail (its the Blank White Eyes or Wide Eyes and Shrunken Irises that you need to really look out for). Griffith, on the other hand, has piercing white slitted irises when he is in his Godhand form that is Femto. It makes his Kubrick Stare all the more terrifying.
 * Ren Suzugamori in Cardfight Vanguard has slits for pupils.
 * When Yakumo from Sazan Eyes draws power from  his eyes become completely white with no pupils at all, along with some other demonic changes.
 * In Kuroko no Basuke, the former captain of the Generation of Miracles, Akashi, has these.
 * When Yakumo from Sazan Eyes draws power from  his eyes become completely white with no pupils at all, along with some other demonic changes.
 * In Kuroko no Basuke, the former captain of the Generation of Miracles, Akashi, has these.

Comic Books

 * The DCU's Spectre sometimes manifests images of skulls where his pupils should be, terrifying those who see him face-to-face.
 * Super Sonic, the resident Omnicidal Maniac in Sonic the Comic had red spirals instead of pupils. In some stories they seemed to reflect his demeanour; when he was at the peak of his evil powers the spirals were large enough to fill his eyes, but when he was good they shrank noticeably.
 * And from Archie comics we have Dr. Finitevus, pretty nice guy...
 * Nightcrawler is sometimes shown with these, but he is the nicest guy! His mother on the other hand...
 * Galactus has always had square irises.
 * Dodge from Locke and Key gets these sometimes.

Eastern Animation

 * In Suur Toll, Vanatühi the devil has three red iris pupils.

Fan Works

 * In The Cartographer's Craft, Peter Pettigrew performs a ritual to immensely increase his power, and his eyes are afterwards described as "yellow, with cross-shaped pupils; a goat's eyes."
 * Nyx in Past Sins, inherited from Nightmare Moon. Who she is. Kind of.

Film

 * The Master in the Doctor Who movie. The last time we saw him in the series, he was fighting off the effects of turning into a cat-like creature with the same result.
 * Megumi the Yurei spirit does this in the American version of Shutter, she has a scene where her eyes widen and her pupils go inhumanly small. Very creepy effect.
 * In Aliens, Lance Henriksen wanted to have his android character sport a pair of Hellish Pupils while performing his Facehugger autopsy, but director James Cameron declared that Henriksen's eyes were creepy enough as-is.
 * Dren in Splice has cross-shaped pupils, as an indicator of her hybrid nature
 * In Final Fantasy VII: Advent Children, when Cloud is suffering from a particularly intense spasm from the Geostigma disease, Cloud's otherwise normal pupils will briefly turn into cat-like slits resembling those of Sephiroth and the Remnants.
 * The eyes of the remnants of Sephiroth are like this all the time. Sephiroth's pupils are also slits, but not as large and catlike.
 * In In the Mouth of Madness, the ax-wielding maniac who attacks Trent early on has eyes with two pupils that overlap one another.
 * In Galaxy Quest, Sarris's eyes are yellowish-green with dual pupils (one large one and a smaller one next to it).
 * An eye with Hellish Pupils appears in the trailer for Battleship.

Literature

 * The mage Raistlin from the Dungeons & Dragons-derived Dragonlance Saga has pupils shaped like hourglasses, a side effect of a magical talent he received when young.
 * Naturally, Raistlin has Eyes of Gold, too.
 * Good Omens: A. J. Crowley has yellow, snake-like eyes (six thousand years ago he was a snake, hence the fact that he occasionally hisses, doesn't blink much, and can do 'odd things' with his tongue), hence his Cool Shades. Crowley is a demon who lives in a fantastic London flat, designed the M25 railway as one of his most evil deeds, and drives a Bentley. His shades are pretty damn cool.
 * Harry Potter: Voldemort has slit-pupiled, red eyes.
 * Mr. Teatime, the psychopathic assassin from Terry Pratchett's Discworld novel Hogfather has jaundiced eyes with creepy pinpoint pupils. The fact that he only has one eye doesn't detract from this - indeed, his glass eye is described as being the less creepy one.
 * Percy Jackson & the Olympians: Ares has these when he removes his Cool Shades. They get hotter as he gets angrier, at one time melting his sunglasses.
 * The Westfolk (elves) from Katherine Kerr's Deverry novels all have catlike eyes (big irises and slit pupils), though they aren't exactly harbingers of trouble... most of the time...
 * All Witchers gain catlike eyes during their mutation. This enables them to see in the dark, but also makes them distinctly more badass.
 * And, coincidentally, in bright light as well (Pointed out in-text, when Geralt's pupils turned into thin slits, giving him an advantage in a fight). A cat's eye not only looks cooler, it's simply more awesome.
 * A somewhat minor (can The Dragon have a dragon?) villain in the X Wing Series, the petty crime lord Zekka Thyne, has red eyes with diamond-shaped pupils edged in gold, which reflect light when he's in the dark. The heroes are very happy to take advantage of this and shoot him when he's trying to sneak around. (It happened twice, and one of them even warned him earlier that if he slipped up he'd be tracked down by his "double-diamonds". No one told him about goggles, apparently.) Justified in that he's apparently some kind of Half-Human Hybrid.
 * The Hot Witch in Alchemy by Margaret Mahy has eyes that initially appear normal, but turn yellow and catlike when examined closely. Somewhat surprisingly, she's a good guy—the antagonist is even creepier.
 * Lord Foul has eyes like decaying fangs. It's not entirely clear what is meant by this simile, but it's probably not anything good.
 * In The Lord of the Rings, Sauron is represented (in visions, and from there as a metaphor) by a great eye, with a slit pupil and yellow like a cat's, and rimmed with fire.
 * The original books are vague about what exactly Sauron looks like at that point in Middle-earth's history, although its evidently nothing pleasant. And it's strongly implied that, unlike Peter Jackson's giant disembodied eye, he's still humanoid: the closest thing available to an eye-witness reports that "He has only four [fingers] on the Black Hand, but they are enough..."
 * We don't know anything about what he looked like when he took vampire/werewolf/elf form. Presumably something like this.

Live-Action TV

 * Star Trek: Voyager: Members of Species 8472, one of Trek's few completely non-humanoid alien races, have cross-shaped eyes. How nasty are they? The Borg are terrified of them.
 * The Silicates (AIs) of Space: Above and Beyond also had crosshair eyes.
 * Those affected with the cheetah virus on Doctor Who.
 * 'Deathwalker' from Babylon 5 had cat's eyes.
 * The X-Files. Seen at the end of "Terms of Endearment"
 * And in "Die Hand Die Verletzt", when the teacher-demon-lady-whatever-thing was carrying out her/its rituals.
 * Inverted on Criminal Minds, when a homicidal taxidermist replaces the realistic glass cat eyes of a preserved bobcat with the real eyes of the man who'd brought the animal in to be stuffed.
 * The Wraith of Stargate Atlantis have both the slitted pupils and the yellow iris. And they are pretty creepy. Well, at first.

Oral Tradition, Folklore, Myth and Legend

 * Virgil describes Charon as having eyes "like hollow furnaces on fire."

Puppet Shows

 * Kermit the Frog obviously isn't evil (except for in the last sketch here), but that doesn't stop him from having these kind of eyes.
 * And no, they're not like real frog eyes, unless there's some particular frog species with weird eyes.
 * They may not look exactly like Kermit's eyes, but there are. Frog eyes can get pretty strange as they often have horizontal pupils and are the same colors as the rest of the frog's face.

Tabletop Games

 * One piece of Warhammer Fantasy Battle art depicts a pair of eyes with the eight-pointed star of Chaos for pupils. As a general rule: if you are in the Warhammer world and you see someone with those symbols in their eyes looking at you, it may be time to take a long vacation. And it's probably best if you don't stop to pack.
 * Urik von Kharkov, a Ravenloft darklord who can change into a panther, develops slitted pupils when he gets angry.

Video Games

 * When Chris gets possessed by Orochi in The King of Fighters '97, his eyes become slitted and yellow; however, this only part of the transformation.
 * This editor saw him with Red Eyes, Take Warning in that form...maybe it was changed to that in '98 and/or '02.
 * Goenitz also gets slitted pupils before fighting in The King of Fighters '96; and in the Neo-Geo pocket games, the Heavenly King version of Yashiro and Chris also have these kind of eyes. Sheremie? Who knows.
 * Beckett from Vampire: The Masquerade Bloodlines has slitted cat pupils and eyes that are completely red—a side-effect of his vampire clan. He is, however, neither a villain, trouble, nor particularly sinister—the worst he'll do is be sarcastic at you.
 * Sephiroth, Big Bad of various incarnations of Final Fantasy VII, has the slitted cat-like variety, compounded with those oh-so telling "Mako" eyes.
 * His eyes were always like that, even before he turned bad, presumably because of Jenova's cells. This is especially evident in Crisis Core.
 * Many of the demons in Disgaea have this. Rozalin of the second game  takes it a step further by having white slitted pupils.
 * (Human) Princess Sapphire has white star-shaped pupils. Seeing as she's conclusively off her nut, it would be safe to call them hellish.
 * Rikku and the Al Bhed people of Final Fantasy X have spiral-shaped pupils. They're not evil, though, just quirky and a tad ornery. Yuna has one eye like this, as she's half-Al Bhed (Rikku is actually her cousin, in fact).
 * Solid Snake has slit pupils in the Nintendo GameCube remake of Metal Gear Solid. However, they only appear in that particular game and he's not terribly evil despite the violence supposedly latent in his genes.
 * The first step of Konishi's One-Winged Angel in The World Ends With You is heralded with her taking her glasses off as her eyes turn into green cat's eyes. Her monstrous form, appropriately enough, is Tigrus Cantus.
 * Minamimoto's eyes, on the other hand, are constantly yellow and catlike—his form is Leo Cantus.
 * Albert Wesker's cat eyes in the Resident Evil series, first seen in Code Veronica. Possible Shout-Out to Michael Jackson's Thriller.
 * The cover art of Resident Evil 2 features a zombie with slit pupils holding the "2" part of the title.
 * If you pay close attention to the skits in Tales of Symphonia you'll notice that Presea's pupils are black while the pupils of the rest of the cast are white. She's not evil though.
 * Mephiles' eyes after taking on the shape of Shadow the Hedgehog in |Sonic the Hedgehog 2006. Despite this combined with him not having a mouth and his evil-sounding voice, Silver doesn't seem suspicious in the slightest during their first meeting.
 * The trope becomes even more apparent in Mephiles' crystalline form.
 * Humanoid Shadows in Persona 4 have these. Once denied by their human counterparts (the last step to being killed by one is to shout "YOU'RE NOT ME!"), they turn into full-out Glowing Eyes of Doom just before the transformation.
 * Lara's Doppelganger in Tomb Raider: Underworld has pupils that constantly reflect light like a cat's.
 * The PlayStation game, Lost World: Jurassic Park (loosely based on the movie) allows the player to control multiple characters throughout the game, including three dinosaur characters. The strength of the dinosaur characters' attacks are governed by an "Instinct" meter in the upper corner, which takes the form of an eye. The eye starts off as a green iris with a large, circular black pupil. The character can pick up items to change this, including a Full Instinct item, which makes the eye in the corner a blazing red, with a slit pupil. This Instinct boost causes the player's attacks to be significantly stronger, and the player must kill enemies in quick succession in order to keep the Hellish Pupil, otherwise the eye color begins to transit backwards through orange, yellow, and back to green, with the pupil changing back to a more circular shape. Obtaining Instinct and keeping it maintained is an important part of gameplay, as having full Instinct can make bringing down even the hardest of bosses a matter of only attacks hits, so it really pays the player to obtain the Hellish Pupil and keep it that way.
 * from Yggdra Union's eyes were probably like this, considering that the one that's in the Gran Centurio has a slitted pupil.
 * Klonoa from his eponymous video game series, is a heroic example, with catlike slit pupils surrounded by equally catlike golden irises. The pupils have widened somewhat over the course of several installments and spinoffs and currently resemble Sonic the Hedgehog's eyes more than the full-on cat eyes he had in his first game.
 * Then again, Klonoa IS a Cat.
 * Date Masamune from Sengoku Basara has slitted pupils (well, one at least), despite being an ordinary human by the game's standards, and though questionably insane he's by no means evil. However he is often referred to as a "dragon", and whether this is to be taken literally or not his design sports a lot of dragon motifs.
 * Touhou Project offer Nue, who's missing her pupils almost entirely (they're just darker red spots). Despite ZUN being famously bad at character art, he does normally color eyes correctly, so much of the fandom accepts this as intentional.

Visual Novels

 * Rider in Fate/stay night possesses square pupils, and as they're usually covered in the original game people only realize this right before being Taken for Granite by her powers.
 * Gilgamesh from the same game has slitted pupils, apparently just to make him look more threatening.
 * So does Lancer; it might be Fate-continuity shorthand for marking out someone who's got
 * Rin has slitted pupils when she's angry. While she is a magus, it's probably artistic license more than any indication of anything abnormal.
 * And she has box pupils in Shirou's dreams.

Web Comics

 * Last Res0rt: Jigsaw's pupils and irises turn red, with the whites replaced by black, when she really loses her temper. It's one of the signs that she's a vampire, and her powers seem to get a significant boost when it happens. It's not something she wants people to see, though - she's trying to keep the fact that she's a vampire under wraps.
 * Vriska Serket from Homestuck has one normal eye and one eye with seven pupils, though she considers them to be seven different eyes. It fits the "hellish" part perfectly, since she's the Token Evil Teammate (and considering where she lives and who her teammates are, that's really saying something!) It also fits her "eight" Numerological Motif.
 * Kit from The Dreadful has vertically slitted eyes, to go with her demon girl motif.
 * In El Goonish Shive, the transformation from normal pupils to this is used here to signal the beginning of Grace's (almost) Unstoppable Rage.
 * Most Hellhounds in Wurr spot these. They are nicer than they look.
 * Eerie Cuties (as well as spin-offs) got a few people like this, it's rarely visible. Rather unsurprisingly, seeing how it's about All Ghouls School — Delacroix are vampires, Ace is a werecat, Tabitha is a were-ocelot, Brooke is a weresnake Melusine, Chloe and Tia are demons…

Web Original

 * In The Gamers Alliance, Shyralis has snake-like slitted eyes, and this disturbing appearance is part of the reason why she was bullied as a kid.
 * In More Tales of MU, a dragon is described as having "jagged diagonal pupils".
 * Tetras from The Motley Two, a descendant of Homestuck's Vriska Serket described above, has four pupils in total (three in the left eye). Her Numerological Motif is, of course, four.

Western Animation

 * In Code Lyoko, the symbol of the AI antagonist XANA is a stylized eye. Humans and animals possessed by XANA have their pupils replaced by this symbol. (It also appears somewhere on all of XANA's monsters in the virtual world, usually as a weak spot.)
 * The version of Adrian Toomes (A.K.A. the Vulture) seen on The Spectacular Spider-Man has comma-shaped pupils, which look particularly odd when he's out of costume.
 * Megatron in Beast Wars hasn't just got the regular red eyes, he also goes around with reptilian pupils when he's in Robot Mode. This becomes especially noticeable when he goes Transmetal.
 * Gentle Giant: Rhinox gets Red Eyes, Take Warning Glowing Eyes of Doom slit-pupiled eyes when he is temporarily turned into a Predacon.
 * Several characters get these in the Batman Beyond episode "Splicers", from getting animal DNA "spliced" into their own.
 * Derek Powers had this even before becoming Blight. His eyes were black with white pupils.
 * Bender from Futurama has square pupils. Okay, so all of the robots do. Not like they're the paragons of future society, though.
 * All glory to the Hypnotoad!
 * Jinx of Teen Titans has narrow, cat-like pupils, but she's not exactly "evil," just fell in with the wrong crowd.
 * Disney's The Legend of Tarzan played fast-and-loose with the works of Edgar Rice Burroughs in many ways. The main example of this trope? Queen La, now melded with the Leopardmen and given a pair of catlike eyes.
 * Professor Screweyes from Were Back a Dinosaurs Story. True, his left eye is actually a screw buried deep on his eye socket, but the fact that the screw's slit is in a vertical position (instead of in a diagonal or horizontal one) pretty makes it look like the pupil of a snake or a cat.
 * Who Framed Roger Rabbit?? has  such scary eyes that they could count as Eldritch Abominations.
 * Chase Young from Xiaolin Showdown.
 * Nightmare Moon from My Little Pony: Friendship Is Magic has glowing cat eyes of doom.
 * Maybe they help her see in the dark?

Real Life

 * Cuttlefish have W-shaped pupils that sense polarization rather than color. As for "channeling something nasty"... KiLL ThE PhYsIcIsTs.
 * Goats have rectangular pupils. Creepy, rectangular pupils.
 * Anyone who has ever kept goats knows there's a reason that slit pupils are associated with evil and trustworthiness.
 * Those are standard issue for hoofed mammals. It allows them to see a wider field of view, and spot any predators sneaking up on them.
 * Nobody's saying there's no good reason for it. But they aren't exactly "standard issue"... most hoofed mammals do not have creepy rectangular pupils. For example, every single one of the friendly happy fluffy animals we have on farms (except goats.)
 * Horses, cows, and sheep have rectangular pupils too, actually, and pigs' pupils are oval. Goats just tend to have lighter-colored irises that make their pupils more obvious.
 * People who have undergone cataract surgery are often left with keyhole-shaped pupils on the surgical side.
 * A certain defect in the iris can result in a cat's eye-like appearance.
 * Cats, let us note for completeness, only have the slitted eyes when the lights are good. Their eyes, like ours, expand and contract the pupil as necessary - theirs are just slitted for most of the time. Look at your cat the next time the lights are low and you'll see a very round pupil.
 * For example.
 * Having Vincent Price laughing at some point would've made it less creepy...
 * Reptilian humanoids comprise a common motif in mythology, folklore, science fiction, fantasy, conspiracy theories, ufology, and cryptozoology. If you type "reptilian shapeshifter" into Youtube, you'll stumble across a schizophrenic world of reporters, celebrities, politicians, and others who can't stop their eyes from becoming sinister-looking slits. For instance, here. The shapeshifting doesn't stop with their eye shape, but also eye color, facial structure, and an occasional hissing sound.
 * Koalas, oddly enough.
 * Pandas are called a word that literally means "bear cat" in China, because they have slit pupils unlike the round pupils that are standard for bears.
 * In general, venomous snakes are more likely to have slit pupils, and non-venomous snakes usually have round pupils. For example, vipers. This isn't always the case, however; cobras have round pupils.