— Rubeus Hagrid, Harry Potter and the Philosopher's Stone
The best-selling secular book series of all time.note Unless you count the Old and New Testaments of The Bible and their constituent volumes as a "series".This series of seven children's and young adult novels by J. K. Rowling exploded onto the world literary scene in the late 1990s and has become a phenomenon unlike anything seen before in publishing. Blending fantasy with the nearly extinct British Boarding School genre, it made a literary superstar out of its ex-schoolteacher author, and the characters and settings she created have permanently entered popular culture the world over. Needless to say, there is a multimedia franchise revolving around them, consisting of a series of films, video games and various other merchandising tie-ins, but at the heart of it are the books.The basic story is simple: Harry Potter is a seemingly normal schoolboy, living with his resentful, abusive aunt and uncle after being orphaned in his infancy, who on his eleventh birthday discovers he isn't really normal at all. His parents were both powerful wizards, and Harry himself is the renowned defeater of Voldemort, would-be Evil Overlord of the wizarding world. Voldemort had attempted to kill Harry when the latter was only a year old, but for unknown reasons, the curse he cast at the boy afflicted himself instead, killing him... sort of.Harry goes to Hogwarts, the great school of magic, and is happy. There are the normal school troubles — bullies, unpleasant teachers, the three-headed dog guarding a mysterious something — but nothing serious, until he sees a dark shadow creeping through the forest. Investigating, he eventually discovers that Voldemort did not truly die. Though his body was destroyed, his spirit clung to life, seeking ways to return from death and resume his campaign of terror.
Tropes specific to books, other media, and characters in the series:
Abusive Parents: While not his biological parents, the treatment Harry receives from Petunia and Vernon Dursley is nothing shy of abusive.
Academy of Adventure: Given that Hogwarts is not only a school, but where most of the most powerful and influential wizards and the most ancient secrets make their home, this is pretty much to be expected.
Achey Scars: Though the pains go away after Voldemort's death.
Action Girl: Hermione, especially in Prisoner of Azkaban and Deathly Hallows. Tonks, Luna, Ginny and even McGonagall also fall into this trope. For the most part, this is more extreme in the films. Particularly with Hermione—otherwise known as the Pink Granger.
Adoring the Pests: The Weasley family adopts a rat named Scabbers, who they thought was a wild rat at the time. (Turns out it was really a shape-shifted form of Peter Pettigrew.)
Adorkable: Luna, and maybe Neville if you count him as a geek. Ron is sometimes seen as this too.
Adult Fear: This series, despite being aimed at children, has plenty of moments that scare the parents more than the kids, and a lot of them have to do with child abuse, Parental Abandonment, and not being able to protect or take care of your own children. Most of this probably came from Rowling's own fears as a mother (and especially as a single mother, having broken off an abusive marriage).
Aerith and Bob: The "Muggle" first names range from Dudley to Hermione; the wizarding ones, from George to Xenophilius. All in the UK. Same with the wizarding last names, which range from Potter and Black to Slytherin and Dumbledore. The old pureblood families are the ones to have the strangest names usually and they also tend to have themed names. For example, the Black family and their various offshoots named their children after constellations and stars.
After School Cleaning Duty: This is often given as a detention at Hogwarts. There is usually a requirement that the cleaning must be performed without magic.
Allergic to Evil: Harry's scar burns when Voldemort is angry and/or killing someone — or nearby.
Alliterative Family: Albus, Aberforth, and Ariana Dumbledore. Marvolo, Morfin, and Merope Gaunt. Padma and Parvati Patil.
Alliterative List: The Three D's of Apparition: Destination, Determination and Deliberation.
Alliterative Name: Cho Chang, Colin Creevey, Dudley Dursley, Filius Flitwick, Gregory Goyle, Luna Lovegood, Minerva McGonagall, Pansy Parkinson, Padma Patil, Parvati Patil, Peter Pettigrew, Poppy Pomfrey, Severus Snape, William (Bill) Weasley. And those are just the ones that show up in multiple books; but let us not forget the four founders of Hogwarts: Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw and Salazar Slytherin. And there are also the ghosts: Nearly-Headless Nick, The Fat Friar, The Bloody Baron, and Moaning Myrtle.
All of the Other Reindeer: In book 1, Harry is hated near the end for helping his house lose 150 points. In book 2, Harry is hated because his fellow students think he's attacking them. In book 4, Harry is hated because his fellow students think he sneaked his way into the Triwizard Tournament. In book 5, Harry is hated because all the students think he's an attention-seeking brat. In book 7, Harry is labeled "Undesirable No. 1" by the government.
All Witches Have Cats: A cat is one of the animals which wizarding students can bring as a pet to Hogwarts. In this case the cats are merely pets, not familiars. A Witch and teacher, professor McGonagall, can turn into a cat. Both Hermione and Umbridge own cats, the latter of whom doubles as a Crazy Cat Lady. There was also a Crazy Cat Lady who lived near the Dursleys who turned out to be a Squib.
Alternate DVD Commentary: No, this doesn't go on the Film page — Mark Reads Harry Potter, reviewing the books a chapter at a time. It's genuinely hilarious and does very well to remind us all what it was like to read the books for the first time.
Ambiguously Evil: Snape. He's a deeply unpleasant fellow with an extremely transparent bias in favor of the Slytherin house (which is not seen in a positive light—see Ambition Is Evil below.) He also has an intense dislike of Harry Potter (which turns out to be not only for somewhat complicated reasons, but is also tempered with an odd sense of loyalty and protectiveness) This results in Harry and friends swiftly jumping to the conclusion that Snape is one of the bad guys, especially in The Sorceror's Stone, The Chamber of Secrets, The Half-Blood Prince, and The Deathly Hallows (and they don't really trust him in the slightest in Prisoner of Azkaban or The Order of the Phoenix, either.) The Goblet of Fire is the only book in the series that doesn't seem to go out of its way to villify Snape in some fashion, at least in Harry's eyes. It doesn't help that the events of the books have a knack for making you think that Harry's suspicions might be well-founded, at least until The Reveal at the very end. This comes to a head in The Deathly Hallows, in which Snape has pulled an apparent full-blown Face-Heel Turn by returning to the service of the Death Eaters. However, in the very end of the book, as he lies dying, he gives Harry his memories, revealing that his murder of Dumbledore was in fact a Mercy Kill, and he's been on Dumbledore's side the entire time.
Ambition Is Evil: The usual trait of those put in Slytherin House. Some fans argue this is less about ambition being bad than about the serious lack of high-profile "good" house members.
And Your Reward Is Clothes: A house elf is freed from its master if it is given an article of clothing, which is actually sort of an inversion; the clothing itself isn't the reward (at least, not the only reward), but rather a symbol of the reward.
Animate Dead: Inferi, first mentioned in Order of the Phoenix.
Animal Motifs: An Animagus's animal form generally fits their personality. J.K. Rowling has also stated that Animagi don't get to choose what animal they turn into.
Anonymous Benefactor: Harry had at least four: Dumbledore gave him the invisibility cloak. Sirius gave him a Firebolt. Barty Crouch was a malicious benefactor who helped Harry by proxy. Snape left the Sword of Gryffindor in the woods for him to find.
Anyone Can Die: Not so much in the earlier books, but after Goblet of Fire, all bets were off. By the time book seven was announced, and Rowling herself stoked the fires by claiming that more people would die, entire websites were devoted to betting on which major characters were going to bite the big one, including the three main characters.
Arbitrary Skepticism: Luna Lovegood is constantly going on about the bizarre magical creatures her father writes about in his magazine. Even in a world where there's magic, dragons and the like, hardly anyone else believes they exist.
Which, in a way, is clever. Even in a world full of fantasy and magic, cryptozoological creatures and conspiracy theorists are still going to spring up, because human imagination is unlimited.
Hermione's response to the legend of the Deathly Hallows is this. In a world where you can't walk an inch without some magical object turning up is it so difficult to believe that there exist three objects which are a little more magical than usual? Hermione is the character who brought TIME TRAVEL into the story, for heaven's sake!
Somewhat justified, because the Deathly Hallows were featured in a story for little children and there was rather scant physical evidence for their existence. It is also postulated that they aren't actual objects stolen from Death himself, but rather inventions of a few particularly talented wizards.
Whilst Hermione's objection may seem silly to us, Genre Savvy as we are, bear in mind that the Deathly Hallows contradict the mechanisms of the Wizarding World as they are commonly understood by its inhabitants. It is a fundamental rule of magic that no magic can raise the dead (to take but one example). Thus, something that allegedly raises the dead is as alien to a wizard as something that could ignore the laws of thermodynamics would be to a Muggle.
Arson, Murder, and Jaywalking: How the House "points" system at Hogwarts works. Later, we discover that this is how the Ministry of Magic treats "crime" in general.
To elaborate, there appears to be only one wizard jail for UK wizards to go to. The very act of just being there is severe psychological torture, as every happy, positive thought you've ever had is forcibly removed from you, leaving you with nothing but the worst memories of your life. You even forget that this might end. Basically, any crime that merits more than a fine warrants Azkaban. And it's even used for preventative detention of suspects.
The Artifact: The House Point system is this. In the first book, winning the House cup was serious business. But as the war against Voldemort gets more prominent, the House cup fades towards the background. In Harry's last few years at Hogwarts, it isnt even mentioned who won at all.
J. K. Rowling, says that "magic is a dominant and resilient gene." Given the number of wizards born to Muggle parents (and the extreme rarity of the reverse), this blatantly flies in the face of middle school genetics. You could say that A Wizard Did It (it is magic, after all), but a better explanation would perhaps be that magic is recessive and that squibs have mutations that block or repress the magic gene. This may be a whole class of subtrope: treating "dominant" and "recessive" as synonyms for "awesome" and "lame", rather than their proper meaning in genetics, which are "works even if you only get one" and "only works if you get two".
Though on another hand, it seems that whenever a wizard has a child with a muggle, the child is magical which, unless they were all just really lucky, would mean magic IS dominant. Either way it just doesn't add up.
Both the book and movie of Philosopher's Stone feature a snake that winks at Harry. Snakes can't wink.
Audience Shift: Rowling has said that as Harry and the original audience grew older, the maturity level of the books would "grow" as well, making it so that while the early books are straight children's literature, the later ones fall more into the YA genre. Though it will be tricky for future generations of Potter fans, it makes sense when you realize the series took over a decade to be released in full; the 10-year olds who were reading Harry Potter and the Philosopher's Stone in 1997 would be 20-year olds by the time they were reading Harry Potter and the Deathly Hallows in 2007.
Author Avatar: Hermione is, by J. K. Rowling's own admission, an exaggeration of herself when she was younger. Rowling says she was a bit of an Insufferable Genius in her younger days but gradually mellowed out, much as Hermione does over the course of the series (this may be why, of all the young performers in the Potter movies, Rowling is closest to Emma Watson). Rowling has admitted that each of the three main characters are aspects of herself.
Awesome, but Impractical: Animagus transformation is largely considered more trouble than it’s worth. To begin with, it’s a particularly difficult branch of the already particularly difficult art of Transfiguration, and the consequences of botching the job are said to be disastrous. Even when carried out successfully, one is instantly labelled a criminal unless they give full public disclosure of their skill and animal form to the government to prevent misuse, which rather jives with the fact that stealth and inconspicuousness are the skill’s main use. Even with all this, the form taken by the Animagus is fixed and determined by their personality, so they can easily end up with a useless conspicuous form for all their trouble. Cats, dogs and beetles? Useful and mundane-looking in any backdrop. Huge deer? Not so much.
Bad Powers, Bad People: Double subversion. Parseltongue is usually an ability only found in evil wizards. Harry is good and runs into trouble when people assume he's bad because he possesses it. It turns out in the last book that the reason Harry has it is because it belongs to Voldemort, who gave him the ability when he accidentally turned Harry into a seventh Horcrux. And when Harry loses the fragment of Voldemort's soul residing in his body, he supposedly loses the ability with it.
Perhaps played straight as well with Dumbledore. In the first book, McGonagall suggests that Dumbledore could do everything Voldemort was capable of if he were less noble. (Whether this means that Dumbledore can't do them, or simply wouldn't, is not answered.) For starters, Dumbledore knows Parseltongue; he can't speak it because he wasn't born with it, but he can understand it. Likewise, in the seventh book, Voldemort states that what he will achieve could have been Dumbledore's, implying that he could have been as "great" if he weren't such a sentimental old fool.
To some degree it's debatable how much it's true that only those born with Parseltongue can speak it. Dumbledore is able to understand it without being able to speak it; Ron can speak it (by imitating Harry) without understanding it. If those who aren't born Parselmouths can do each one individually, it's reasonable to assume that someone might eventually figure out how to do both.
Badass Family: The Weasley siblings already include a curse-breaker, a dragon rancher, and a prefect when the books begin, and all of them go on to be successful in various fields. And let it be put on record that the matriarch of this family, Molly, kills Bellatrix, who is the second most powerful Death Eater after Voldemort himself. The fact that they happen to be close friends of Harry Potter (who himself is considered a member of the family, in more ways than one) certainly helps.
Barred from the Afterlife: Ghosts are people who either refused or were too scared to accept death and move on. Apparently, there's no take-backs later on if you change your mind.
Batman Gambit: Voldemort's plan in the Half-Blood Prince and Dumbledore's plan revealed near the end of Deathly Hallows.
Battle Couple: Many. Examples include Lupin and Tonks, Harry and Ginny, Ron and Hermione, and Arthur and Molly.
Beam-O-War: Spells have been known to clash and cancel each other out, though there's at least one instance of two characters firing spells at each other where the beams hit each other and ricochet off at angles, each hitting the person standing right next to the intended target.
Hurting Harry or any of his furry friends will get Hagrid very angry. When Fang got hit by a spell, Hagrid hurls the perpetrator ten feet in the air.
"NOT MY DAUGHTER, YOU BITCH!"
Harry doesn't take kindly to willing parental abandonment, given his experiences as an orphan. Also, if you don't want to end up as a balloon or have your nose broken, don't even think about insulting his dead parents.
Dumbledore will kindly accept horrible slurs against him and remains civil to his enemies even when dueling them, but reacts furiously if any of his students are threatened.
Dobby is fiercely protective over Harry ever since Harry freed him and his trademark is "You shall not harm Harry Potter!" He is so devoted to Harry that he would risk his life (and lose it) for Harry and the others to escape the Malfoy's manor.
"Kreacher will not insult Harry Potter in front of Dobby! No he won't! Or Dobby will shut Kreacher's mouth for him!"
Neville flips out when Malfoy says they should send Harry to St. Mungo's as they have special floor for people with brain damage. Considering what happened to Neville's parents, this is understandable. Pretty much any mention of Neville's parents in a negative light will result in a beatdown that even Death Eaters didn't expect.
Harry doesn't take insults to his parents very well. And when Bellatrix killed his godfather/father figure and when someone insulted Professor McGonagall and spit at her, he truly lost it and sent the Cruciatus Curse at said perpetrators.
Harry also doesn't like to be left out of things, going into ALL-CAPS RAGE◊ because he got stuck at the Dursleys', while Ron and Hermione got to hang out with the Order at Grimmauld Place.
Big Bad: Voldemort. Harry's nemesis, Dark Lord, leader of the Death Eaters, and the initiator of two Wizarding Wars. Almost everything bad that has happened from the past 50 years to the Wizarding World can be traced back to him.
Most obviously Albus Dumbledore at the start. Head of the school, known as the most powerful wizard of the age and the only one Voldemort feared, and an important mentor figure.
Harry himself in Harry Potter and the Deathly Hallows. Even though he does not exactly lead anyone, he continues to inspire hope and is a rallying point for the students of Hogwarts, Dumbledore's Army, and the Order of the Phoenix. In the practical sense, however, Moody and, after he dies, Kingsley, seem to be Dumbledore's designated successors.
Off-screen, Neville is this for Hogwarts during Deathly Hallows: it's implied by the way he talked that he stood up and took a lot of crap so the other students wouldn't have to, he was the only leader of the DA to remain at school for the entire year, and during the Second Battle of Hogwarts, he was explicitly shown leading an attempt to kill Death Eaters en masse using Mandrakes.
McGonagall also serves as a Big Good at Hogwarts in Dumbledore's absence: she protects the students from the sadistic Carrows, overthrows Snape, and leads the resistance against Voldemort when Harry returns.
Bigger Bad: Lord Voldemort, the official Big Bad of Harry Potter, is in this role instead sometimes:
Harry Potter and the Chamber of Secrets. If you consider each Horcrux as a separate person, the main portion of Voldemort's soul (residing in the disembodied Voldemort himself) was a Bigger Bad in this book. Tom Riddle was more a manifestation of Voldemort's will, and in any way acted independent from him (although in his interests).
Harry Potter and the Prisoner of Azkaban. He wasn't directly involved in that book's events but it's believed Sirius Black, the Death Eater who helped Voldemort to kill Harry's parents and later killed Peter Pettigrew and several muggle bystanders, was trying to kill Harry in hopes it'd somehow restore Voldemort. Then it was revealed Peter Pettigrew faked his death and framed Black but it still counts for the trope since Voldemort killing Harry's parents led to Sirius being imprisoned and Peter faking his death.
Harry Potter and the Half-Blood Prince doesn't feature Voldemort at all, and all his actions take place outside the main events of the plot. The Big Bad of the book eventually turns out to be Severus Snape, who kills Dumbledore and set most of the events in motion to further himself in Voldemort's eyes.
Bittersweet Ending: Prisoner of Azkaban. Even though Sirius managed to convince Harry, Ron, Hermione, Dumbledore, and even Snape of his innocence, Wormtail still got away, preventing Sirius's true exoneration before the Ministry and eventually bringing about Voldemort's resurrection a year later.
Deathly Hallows. Even though Voldemort is finally dead, and most of the Death Eaters are killed or captured, Hedwig, Moody, Dobby, Colin, Fred, Lupin, and Tonks all died in the process.
Black and White Morality: The series starts out this way. Dumbledore is the Big Good, Harry and his friends are the heroes, the other students are generally nice except for the Slytherins, and Voldemort is the Big Bad. As the series goes on, it adds more and more shades of gray with turncoats on both sides, a corrupt government opposing Voldemort, heroes paying evil unto evil, and Harry discovering that his father and Dumbledore have...complicated backstories.
Harry occasionally slips towards this in battle; when crossed or when his friends are threatened, Harry can become quite pitiless, instinctively resorting to the nastiest/most powerful curses he can think of (save Avada Kedavra). He even casts the Cruciatus Curse at a few points (though he never uses it very effectively; as Bellatrix explains after he tries it on her, in order to cast an Unforgivable Curse successfully, you have to really want to go through with it). Justified, as he is a teenage boy in way over his head.
Black Sheep: Sirius and Andromeda to their respective families.
Percy is the only member of the Weasley family who is not friendly and outgoing.
Blasting It out of Their Hands: The Expelliarmus spell, which is intended for exactly this purpose. Amusingly, the spell seems capable of disarming a person of anything, whether it's a weapon or a book.
Blond Guys Are Evil: Played straight with Draco and Lucius Malfoy, Barty Crouch Jr., Dudley Dursley, and Gilderoy Lockhart. Averted with Ernie Macmillan.
Bloodless Carnage: Avada Kedavra's lack of leaving physical injuries on bodies provides a convenient excuse for not describing much blood and gore, so most deaths in the series partially play this straight because they are bloodless and painless. That said, there are spells for dismembering, and they can get bloody indeed.
Boarding School of Horrors: At times, Hogwarts can be quite a dangerous place. Made obvious when, on Harry's first day at school, there's an announcement to the student body to please do not enter the third floor corridor unless you want to die horribly.
It has been in the past: In an early book Filch talks about how they used to string students up. In book 4, Moody is admonished for punishing a student with transfiguration, but implying it was allowed at one time.
This is in no small part due to the dangers of practicing magic on its own. Many spells can be very dangerous, especially in the hands of someone who doesn't know what they are doing.
Hogwarts becomes this full-time when Umbridge, and later Voldemort, take over. Deathly Hallows goes out of its way to explain how horrible it's become by saying that some prefects used the Crutacius curse on first years (about 11 years old) for refusing to use it themselves in the now-mandatory dark arts class.
Mentioned frequently by Dumbledore, that Tom Riddle / Voldemort never bothered to study those powers he already considered useless, meaning Voldemort's plans could always be defeated by such "trivial" things as Love.
Could also be because he's working with only one-seventh of a soul, which may be why he often seems so much less than human—almost a parody of a human. It wouldn't really be that surprising if there were intelligence-related side effects as well.
He also followed #101, by not delegating away the task of killing "the infant who is destined to overthrow [him]", but trying to kill Harry himself. That workedrather brilliantly.
In perhaps his final big villain stupidity moment, he makes one of his lackeys check to see if Harry is dead, not doing it himself or using a messy non-magic way of ensuring his greatest opponent remained dead.
Book Dumb: Ron and Harry really aren't diligent students, though when they do try they prove to be quite adept. Fred and George are even worse academically, but they're experts in magical joke item inventions, which eventually gets them far in the business world.
Harry's life with the Dursleys. When he was one, having recently lost his parents and beaten Voldemort, Hagrid brings him to Privet Drive riding Sirius' magical motorcycle. When he is about to become seventeen, with the magical protections about to fall, Hagrid is the one that carries Harry out of Privet Drive on the same motorcycle. Hagrid even comments it.
Also, in book one: Ron: "Are you a witch or not?" In book seven: Hermione: "Are you a wizard or not?"
The entire series effectively begins and ends with Voldemort getting the Avada Kedavra curse reflected back at him by Harry.
Boomerang Bigot: Voldemort; one of the goals of the Death Eaters was the elimination of any wizard who wasn't pure-blooded, especially if they were Muggle-born, but Voldemort himself was a half-blood. But then, he is based on Adolf Hitler (see below).
Snape is a double hitter — in his youth, he was highly prejudiced against Muggles and Muggle-borns despite being a half-blood himself and in love with a particular Muggle-born; as an adult teacher, he mocks Hermione for being, as he once put it, "an insufferable know-it-all" — ironic coming from Snape, who is himself an Insufferable Genius.
Brain Bleach: The reason why Rowling has yet to reveal the exact method of creating a Horcrux. It supposedly made one of her editors vomit. (For note, one of the steps is committing murder in order to split your soul to place it in the Horcrux. Murder is one thing, but the entire process is implied to involve crossing the Moral Event Horizon, and it's certainly treated as such in-universe.)
Bribing Your Way to Victory: In-Universe, Harry is constantly praised as the best Seeker in the school, and maybe the best player for several years. However, twice in the series, Harry is gifted broomsticks that are demonstrably faster and more maneuverable than his opponents'.
...Kind of. Harry's initial feat of Seeking that earns him praise is performed on a school broom, which are pretty much universally derided in-universe. He then receives a good broom—but not so good a broom that it would make up for a lack of skill on his part. Then, in second year, he wins against a whole team of players on better brooms than his own, and with a serious disadvantage. (The Bludger is cursed to attack him.) It's only halfway through the third book that he gets a broom that's a whole class above his opponents', and by that point, I think he's pretty well proved himself.
Brick Joke: In what is perhaps the most elusive brick joke in the series, at the start of book 5, Harry and Dudley are attacked by Dementors. After Harry fights them off, he attempts to explain to his aunt and uncle what happened, only to realize it's hopeless since neither of them have any idea what he's talking about. Petunia finally says, "They guard the wizard prison, Azkaban", and Harry asks how she could possibly know that. Petunia responds with "I overheard — that awful boy — telling her about them, years ago." At the time (and even after finishing the series), everyone simply assumed "that awful boy" to be Harry's father, James Potter. However, at the very end of book 7, we find out that it was actually Severus Snape. While watching his memories, Harry witnesses the scene "first hand", but it's played so quickly and amidst so many other things very few people pick up on it.
Bullying a Dragon: Let's see, there's this giant man standing in front of you. He also possesses Super Strength, jugding by the way he knocked your door down. This is clearly not someone to be messed with, so what do you do? Well, whatever it is, you do NOT threaten your nephew, who up until now has had no idea that he is a wizard, in front of said man, and you do NOT insult a man the giant clearly admires...unless you're Vernon Too Dumb to Live Dursley, of course.
Bury Your Gays: Dumbledore was only outed by Rowling herself, after the 7th book had been released.
Neville "Why's It Always Me?" Longbottom. Peter Pettigrew during his days at Hogwarts, as well.
There is a minor character (Dawlish), who is sort of a background Butt Monkey in that the only time we see him, he gets defeated in one hit, and whenever he is mentioned, he has been cursed or failed in something. This is pretty shocking when you consider he's an Auror, the equivalent of magic police (who above that are also elite dark wizard catchers), and is therefore supposed to be skilled at defensive magic.
Draco Malfoy, Gilderoy Lockhart, Argus Filch, and Dolores Umbridge also fall under this category at times, although they more than deserve it. Quirrell too, until he is revealed to be The Dragon at the end of Book 1.
Also, Hufflepuff House in general.
Ron Weasley, particularly to Slytherins. Harry has also been subjected to this, most notably due to the Rita Skeeter articles.
Not only that, but they have to fully comprehend what they saw — Harry wasn't able to see thestrals when he first came to Hogwarts despite having witnessed the murder of his parents, but he is able to see them when he comes back fifth year after he saw Voldemort kill Cedric Diggory. (It's generally assumed that he couldn't see them at the end of his fourth year because Cedric's death hadn't fully sunk in at that point.)
Cain and Abel: Dudley and Harry, Petunia and Lily, Severus and Lily.
Calling Your Attacks: Played straight at first, but justified in that you have to say the name of the spell in order to cast it. However, it gets subverted when a major portion of the sixth-year curriculum turns out to be learning how to cast spells without calling them, specifically so that you don't alert your enemies as to what you are doing.
Canis Latinicus: Expelliarmus, Wingardium Leviosa, Petrificus Totalus, Riddikulus. There are real Latin spells as well.
Can't Live Without You: Inverted by the prophecy in the fifth book — "Neither can live while the other survives."
Captain Ersatz: While possibly coincidental, the Dementors have a certain resemblance to the Nazgûl of The Lord of the Rings. But they're both based on The Grim Reaper. Dementors are also an allegory for clinical depression—they suck the joy out of everything.
Hermione: "I read about it in Hogwarts: A History."
Moody: "Constant vigilance!"
Umbridge: "Hem hem".
Slughorn: "Merlin's beard!"
Voldemort (in the movies): "NYEAAAAAAAA!"
Category Traitor: The Death Eaters consider wizardry to be in the blood. They also feel that all "real" wizards are obliged to be "loyal" to "their own kind", and thus despise all regular humans, fantasy creatures, and above all else the so-called "mud-bloods": Muggle-born wizards (and later, once they resurface and begin openly fighting the Order of the Phoenix, also any and all wizards who don't agree with the Death Eater ideology's arbitrary definition of a "real" wizard). Unsurprisingly, their contempt for pure-blood and half-blood wizards who care for muggles and mudbloods turns out to become a big part of their undoing, as young Snape loses faith in them because of his love for the "mud-blood" witch Lily Evans.
Cardboard Prison: Azkaban shows this. While in book three it is said that Sirius Black is the first to ever escape from Azkaban, in the very next book it is discovered that Barty Crouch Jr. had been snuck out some time ago, and in book 5 pretty much everyone gets out.
Cerebus Syndrome: Kinda. The darkness of the plot was there from the beginning, but it gets more visible as the story progresses.
Chameleon Camouflage: The Dissillusionment Charm has this effect, and if done well enough can confer actual invisibility. Putting it on a garment is one way to make an Invisibility Cloak, though the charm fades over time.
Chekhov's Armoury: Chekhov's Gun is common in the series, e.g. The Deluminator; fans obsess over details in earlier books, looking for hidden Chekhov's Guns, to the point where J.K. Rowling made a public apology about accidentally giving a minor, unimportant character the same last name as Harry's mum.
Chekhov's Gun: More accurately, Chekhov's Wand. We learn that Harry and Voldemort's wand share a common source for their magical cores; it takes on plot significance from book 4 onward. Also the Vanishing Cabinet, and Godric Gryffindor's Sword. Along with a fair laundry list of other objects. Of the six Horcruxes, we actually see four of them before they are recognized for what they are.
Chekhov's Gunman: Grindelwald, mentioned in the Philosopher's Stone and barely ever brought up again until Deathly Hallows. Same goes for Aberforth Dumbledore, who was first mentioned in Goblet of Fire and first appeared in Order of the Phoenix.
Even better? We didn't know who he was until Deathly Hallows. In both Order of the Phoenix and Half Blood Prince, he is only referred to as "the barman of the Hog's Head," though there are hints to his identity regarding his inappropriate charms on goats...
The name Regulus Black briefly comes up in one of the books, then becomes significantly more important in Deathly Hallows.
Chekhov's Skill: Ron at wizard chess; Harry and his Patronus; Hermione and Ancient Runes (Comes into play in the seventh book, as her copy of Tales of Beedle the Bard was written in runic alphabet); Neville and herbology.
Harry's Quidditch playing. He's good at flying and good at spotting and getting ahold of small golden objects. This comes in handy when he has to catch a flying key in the The Sorcerer's Stone, and when he has to get the dragon's egg in the First Task of the Triwizard Tournament.
Harry's Seeker skills and the generally harmless "Expelliarmus" spell both play key roles in Harry's final defeat of Voldemort.
This is actually mentioned by Ron in the fourth book. He mentions that Harry couldn't help 'playing the hero'.
Chuck Cunningham Syndrome: In the movies, not the books—Percy plays a fairly important role in the first movie, only to drop out of existence thereafter. He appears occasionally in background shots, but any storyline about him is just removed entirely, to the point one might wonder why his parents never talk about that son they once had hanging around their house.
Nearly-Headless Nick doesn't appear after the first two movies either. Whenever he has an important part in later installments, they seem to replace him with Luna.
Likewise with Dobby, at least in the film adaptations of Goblet of Fire and Order of the Phoenix, where the crucial information he provides is instead revealed by Neville. Unlike Nick, Dobby does make a reappearance.
Cold-Blooded Torture: What happens to many characters at the hands of the Death Eaters (mostly Voldemort and Bellatrix), including Neville's parents.
Contrived Coincidence: The Marauders present themselves in their map as "Moony, Wormtail, Padfoot, and Prongs", or MWPP. Is it a coincidence that they die in that order, backwards? Prongs (James Potter) dies on October 31st 1981, Padfoot (Sirius Black) dies in the Battle of the Ministry in June 1996 (Harry's fifth year), Wormtail (Peter Pettigrew) gets killed on March 1998 by the silver hand Voldemort gave him back in 1995, and Moony (Remus Lupin) dies in the Battle of Hogwarts on May 2nd 1998.
Harry Potter and the Prisoner of Azkaban kicks off because 1) the Weasleys won a lottery ticket 2) This gets them a large front page picture 3) Ron's pet rat Scabbers was included in said picture and 4) Cornelius Fudge happened to be carrying that exact issue when he visited Sirius Black.
Conveniently Coherent Thoughts: Subverted with Legilimency, which reveals thoughts in a disjointed manner and requires much training to sort out which thoughts are important.
Particularly that we repeatedly see Wizards are rendered helpless when they are disarmed, which in later books often leads to their death. For some reason, there seems to be an unwritten rule amongst wizards that you can't carry a spare wand.
Justified in story that wands are implied to be sentient on some level and choose their master. If you have a wand that's not yours you'll only be slightly better off than without one entirely.
Given that most Wizards are capable of Apparating, possess cars such as the Knight Bus for those who can't, and possess the ability to carry large amounts of objects in a Bag of Holding, it often begs the question why they bother with the mess of using Owls to deliver their mail. Theoretically a single wizard could serve as the postman to the entire country.
Corporal Punishment: Not unexpected, given the Boarding School setting. Early on, it's played relatively comically, with Argus Filch constantly bemoaning the fact that he's not allowed to string misbehaving students up by their ankles anymore. It gets rather darker later, with Order of the Phoenix featuring a quill that carves whatever you write into your hand, and God-only-knows-what going on at Hogwarts during Deathly Hallows.
Crapsaccharine World: Once you get past the initial cool factor of the magical world, the Harry Potter universe is not an exceptionally happy one. Fantastic Racism of absurd extremes permeates every level of the wizarding world, and the government seems to be run by evil, scheming, political glory hounds (regardless of their allegiance to "good" or "bad"). The justice system is a Kangaroo Court, the regulations on dangerous magic are feeble at best, the very system of instruction in magic carries a high injury/mortality rate, the schools are run by people who think nothing of manipulating their students for years with the express intention of having them throw their lives away, said schools think nothing of employing borderline sociopaths who a stated dislike of and known enjoyment of torturing children, the entire population as a whole seems to have crippling naiveté about the non-magical world (to the point you wonder how they've kept the masquerade going for so long), and the overall respect for human, sapient non-human, or animal life and sanity is appallingly low. The in-universe explanation is that this was a cultural reaction to Voldemort, and that it supposedly went away once he was defeated. Also, it's heavily implied that there's degradation of the "magical" ecosystem and natives, with species like the dragons and giants dying out and forced on to small reservations.
Crazy-Prepared: Hermione, especially with her bag in Deathly Hallows. Also, Dumbledore, in general.
Crouching Moron, Hidden Badass: Luna "Loony" Lovegood may act like she ain't playing with a full deck, but when it comes down to an actual battle... watch yourself. She participates in several battles, but the only time she gets injured the entire series is when a door gets blown off its hinges into her face and she flies across the room.
And Neville Longbottom, Butt Monkey poster boy in the early years, becomes a seriously competent fighter in his own right from the latter parts of the fifth year and on. In the battle of the Department of Mysteries in Order of the Phoenix, he is the only other student besides Harry who stays fighting right up till the end, whereas everyone else gets incapacitated one way or another during it.
Crushing Handshakes: The Slytherin quidditch team captain tends to do this when he shakes hands with the Gryffindor captain at the begining of a match. In the first few books, Oliver Wood was able to give as good as he got, but Angelina and Harry (during their respective stints as captain in the later books) had to keep themselves from wincing.
Cultural Translation: Editors at Scholastic Books forced a change from "Philosopher's Stone" — a genuine item of folklore and alchemy — to "Sorcerer's Stone" for the American editions on the grounds that American children would have no idea what a Philosopher's Stone was. Due to the negative reaction, British terms and slang in the later books, such as "jumper", "taking the mickey" and "snogging", were left in.
Curse: Spells that have a major negative effect are often referred to as a "curse". More minor curses are called a "jinx".
Dances and Balls: The Yule Ball. In both the book and the movie, however, it quickly degenerates into a magical rock show.
Darker and Edgier: The series has gradually gotten darker and darker as the series has matured.
Rowling published three books mentioned in the series — listed up there with the main series — with profits reverted to charity. One looks like Harry and Ron's book, one seems to be a Hogwarts Library title, and another opens with the disclaimer "translated from the original runes by Hermione Granger."
Bertie Bott's Every Flavor Beans, marketed by Jelly Belly. They've also made Chocolate Frogs, complete with cards, among many other candies.
The Vibrating Broom (the link is perfectly SFW, don't worry), which was so quickly pulled from the shelves.
Quidditch. Granted, the brooms don't fly (among other things), but it is a faithful reproduction of the sport, even to the point where college teams compete in a world cup.
Dead Guy Junior: Lots of examples from the epilogue, including James Sirius Potter, Lily Luna Potter (even though Luna Lovegood doesn't die), Albus Severus Potter, and according to Word of God, Fred Weasley Jr.
Deadpan Snarker: Honestly, if you took a shot every time a character made a wry comment, you'd be pretty messed up early on in the series. There are so many examples, it has its own page.
Death Ray: The Avada Kedavra, or the Killing Curse. The reason that Harry is known as "The Boy Who Lived" is because he's the only person in the wizarding world to survive the spell.
Deconstructed Trope: Happens a lot in the series, especially concerning character dynamics. A character is a Butt Monkey? Turns out that they have some pretty depressing baggage and it motivates them to become a total badass later. Another is a Cloudcuckoolander? They are relentlessly teased and bullied over it and have very few friends. Our main man is a Chosen One and Famed in Story? They really hate it. Kid Genius? Is seen as an Insufferable Genius (which they sometimes act as anyway).
Deus ex Machina: In the first book, Harry is saved from Quirell by his mother's own love, which, as Dumbledore explains, prevents cruel and loveless people from being able to harm Harry. This instance is forgivable, however, as Rowling intended this as both a symbol and a moral message. Some people have claimed that there's another one in Deathly Hallows.
Harry pulling the sword out of the Sorting Hat seems like a DEM at first, but then you realize that Harry was asking for help, and Dumbledore stated earlier, just as he was about to leave, that help would come to those who asked for it. It's clear that he was referring to Harry. Dumbledore sent Fawkes with the sword to help Harry.
It's debatable to what extent the Priori incantatem at the end of Book Four is one. It was foreshadowed early in Book One when Ollivander explains how Harry's and Voldemort's wands are connected, but the actual effects of that still come out of nowhere.
Disproportionate Retribution: The treatment Harry received from the Dursleys for most of the eleven years prior to his acceptance into Hogwarts, and occasionally afterward as well. He was confined to the cupboard under the stairs just for existing, yelled at for asking questions or innocently mentioning strange dreams, and punished (up to and including being denied meals) for exhibiting signs of the hated magic, which he neither understood nor was able to control. For example, in the first book he gets locked in the cupboard for much of the summer just for talking to a snake after the "vanishing glass" incident.
Distant Finale: The last chapter of book seven, better known as the Epilogue, takes place 19 years after the end of the previous chapter.
Ditch The Bodyguards: In several of his books, Harry is being threatened by someone (usually Voldemort), and everybody tries to keep him safe. It never works—somehow, for some reason, he always finds his way to the source of the problem to face it himself.
Divided We Fall: The Half-Blood Prince DVD has a chapter entitled "Free Agents", a clever reference to not only Harry and Ron's Quidditch issues, but their romantic lives, as well.
Domestic Abuser: It's implied in Order of the Phoenix that Snape's father was at the very least verbally abusive to Snape's mother, and that this was a large contributing factor in his anti-Muggle attitudes.
Don't Fear The Reaper: According to J. K. Rowling, the Central Theme of the series has always been death. It doesn't really come to the forefront until Harry Potter and the Deathly Hallows, where Dumbledore states that Harry is the Master of Death not because he owned all three of the Deathly Hallows, but rather because through his experiences where he unknowingly gathered all three, he came to realize that death was inevitable and and that there are far worse fates than dying, and accepted his death. The Tale of the Three Brothers, where the legend of the Deathly Hallows comes from, shows that if you try to escape death or are unable to accept the death of a loved one (the first and second brothers, represented by Voldemort and Snape in The Deathly Hallows), then death will be a grueling bastard. However, if you accept death as inevitability (the youngest brother, Harry), then death will greet you like an old friend. All of this stems from Rowling's own experiences with the death of her mother.
Hermione: If you don't stop, I'm going to... Fred: Put us in detention? George: Make us write lines? Hermione: No, but I will write to your mother. George:You wouldn't...
Doorstopper: All of the books from the fourth onwards; the fifth, weighing in at 766 pages for the Bloomsbury hardback edition, is the winner here.
The original American hardcover edition had it at over 800 pages.
Stephen Fry is even credited with the following:
"So if any of you hear someone pronounce her name "Rohw-ling", you have my permission to hit them over the head with — not with Order of the Phoenix, that would be cruel. Something smaller, like a fridge."
Downer Ending: Goblet of Fire, Order of the Phoenix, and Half-Blood Prince.
Deathly Hallows is no picnic either, even considering the fact that technically, the good guys have finally won a complete victory.
Dr. Genericius: A lot of wizards have names ending in "us" : Albus, Bilius, Lucius, Regulus, Remus, Rubeus, Severus, Scorpius, Sirius... It seems to be more frequent in the Pure-Blood families, though.
The Dreaded: Each side has their own. Voldemort is easily the most feared being on the planet, his power and cruelty are legendary. People are terrified of even speaking his name long after he is thought to be dead. Then, of course, there is Dumbledore, who is the only person Voldemort fears.
Dueling Messiahs: Flashbacks reveal that there was once a legendary duel between Grindelwald and Dumbledore. The former wanted to lead the wizards out of hiding while Dumbledore sided with the muggles.
Dying Like Animals: Not just the Muggles, but wizards and witches, too. Minister of Magic Cornelius Fudge is one particularly outspoken ostrich in a bowler.
Early-Bird Cameo: Several supporting characters were mentioned in passing long before their importance to the plot was revealed, among them Mrs. Figg, Mundungus Fletcher, the Lovegoods, Grindelwald, Aberforth Dumbledore, and, of course, Sirius Black and his brother, Regulus Arcturus Black.
Several creatures in Order of the Phoenix were mentioned in Fantastic Beasts and Where to Find Them prior to their appearances, and even Thestrals earned a minor, blink-and-you'll-miss-it reference under "Winged Horse".
Embarrassing Password: The Ministry of Magic encourages people to devise security questions with their loved ones. One of the security questions between Mr and Mrs Weasley is:
Mr Weasley: What do you like me to call you when we're alone together?
Mrs Weasley: Mollywobbles.
The password to Dumbledore's office is always a type of candy. At one point in Goblet of Fire, Harry, trying to get inside, lists off every single magical candy he can think of, only to find the correct one is "Cockroach Cluster".
Enforced Cold War: The House rivalries, especially between Gryffindor and Slytherin. According to the history of Hogwarts' founders, it's actually closer to Slytherin versus everyone else; according to Word of God, it goes down a lot after Voldemort is defeated.
Entertainingly Wrong: In Half-Blood Prince, Dumbledore and Harry both come to the perfectly valid conclusion that Voldemort had tried to get a job at Hogwarts in an attempt to get ahold of an item belong to a Hogwarts Founder for use as a Soul Jar. In Deathly Hallows, Harry realizes they had it backwards, and that Voldemort used the interview to hide one of his Soul Jars in a hidden room on the way to Dumbledore's office. Actually getting the job would've just been a bonus.
Even Bad Men Love Their Mamas: Draco Malfoy's only redeeming quality is his love for his family. While Voldemort is incapable of real love, his mother's sad death is his motivation for some of his crimes.
Narcissa Malfoy's main motivation by the end is making sure her family is safe, to the point where she lies to Voldemort.
Everyone Is Related/Tangled Family Tree: Check out the Black family tree, for starters. The Peverell and Weasley familes are similarly tangled up: the Peverell family contains almost every single wizard, including Voldemort and Harry Potter! Gets to the point where Everyone Is Related both literally and in terms of the trope.
This is implied to be a result of forced intermarrying of pureblood families in order to keep the blood pure. Amongst the many notable muggle discoveries proud purebloods dismiss are the effects of inbreeding. (Even though there are plenty of things, like the health benefits of laughter, that wizards noticed long before Muggles did.)
Step back for a moment and consider this. Draco Malfoy is easily recognised by his curious white blond hair and aristocratic features. When we meet Lucius we see he too has the same hair colour and similar features, not that unusual. However his mother Narcissa has exactly the same unique hair colour and aristocratic features. What are the odds of her and her husband being related?
Harry and Voldemort both had very similar beginnings, and Harry occasionally finds himself sympathetic to Voldemort. Nonetheless, the choices that both of them made sent them in totally different directions. Lampshaded in the film during the disturbing moment when the two of them briefly meld into one image while falling through the air.
Harry also notes parallels with Snape in Deathly Hallows. He refers to himself, Voldemort, and Snape as "the abandoned boys", and notes that they all found a home at Hogwarts. Interestingly, Snape seems to have been set up as the half-way point between Voldemort and Harry.
Bellatrix and Hermione. Hermione is as devoted to Harry as Bellatrix is to Voldemort. Both intelligent and powerful witches, on the opposite side of the good/evil divide; both capable of, and shown willing to go to, extremes for their purposes. (Bellatrix tortured the Longbottoms into insanity to find Voldemort. Hermione comes up with the same method for Harry to communicate with his DA members as Voldemort used with his Death Eaters; she bewitches a DA document so that it will semi-permanently facially disfigure anyone who signs it and later sells them out; she blackmails Rita Skeeter.)
Bellatrix also serves as an Evil Counterpart to Molly Weasley. That was why Rowling said the two fought each other at the end — Bellatrix loved no one (besides her obsession over Voldemort) and Mrs. Weasley was very loving. Love won out. (This was in spite of Bellatrix having all but been set up as Neville Longbottom's Arch-Enemy.)
Voldemort and Dumbledore turn out to have a lot in common.
Umbridge could be considered McGonagall's Evil Counterpart. Both are known for being disciplinarians, but McGonagall is fair and well-meaning, while Umbridge, to say the least, is not. Incidentally, both of them cast a Patronus in the shape of a cat.
While they're on the same side in Order of the Phoenix, Sirius and Snape could be interpreted as this as well. They started out as Gryffindor vs. Slytherin, then they joined opposite sides of the war. Sirius is James's best friend, and Snape had been best friends and had a crush on Lily, and despite the falling out that Snape and Lily had, he and Sirius are incredibly loyal to their said best friends. Heck, both of them even did something really terrible to a close friend of theirs, Sirius's being sending Snape to be torn apart by Remus on the full moon and Snape's being calling Lily a Mudblood. Snape hated his father, and Sirius hated his family.
Harry and Voldemort's respective chosen methods of self-preservation: Voldemort survives through his six Horcruxes, which he created by murdering six people (plus Harry as the seventh Horcrux). Harry survives through his relationships with friends and relatives, six of whom are killed in the act of directly saving his life: James and Lily Potter, Sirius Black, Albus Dumbledore, Peter Pettigrew, and Dobby. Harry and Voldemort act as the seventh Horcrux/relationship for each other: Harry is Voldemort's unknown seventh Horcrux, and Voldemort unknowingly saves Harry's life by creating a blood bond between them during his resurrection in Goblet of Fire; he even "dies" to save Harry's life when he tries to kill Harry in the Forbidden Forest and instead destroys the portion of his soul preserved in Harry.
Harry's wand and Voldemort's wand shared the same core—a phoenix feather, from Fawkes, who only gave two feathers. Then, we have the Elder Wand, which is different entirely. You could write a paper on the connections between Voldemort and Harry, and have it longer than the books themselves.
Ron and Pettigrew. Both are/were close friends to a guy who is/was considered very popular and cool and basically is/was ignored otherwise. Both were hinted to be a little jealous of this. Deathly Hallows implies that Ron, like Pettigrew, has a bit of a lust for power (his interest in the Elder Wand, though Hermione is just as fascinated by it). Unlike Pettigrew, Ron never abandons his friends for power or protection. More importantly, Ron refuses to be an Extreme Doormat and bottle up his frustration, indeed he voices it out and works through it, which Pettigrew never did and so never worked out his bitterness. Wormtail would sell out his friends to curry favor to the next biggest bully for his own ends.
Evil Makes You Monstrous: Tom Riddle (Voldemort) was a handsome student, but by the time he is reborn, he is bald, has pale white skin, bloodshot eyes and slits for nostrils. We see him earlier in a Pensieve memory Dumbledore has of him entering his office to ask to be the Defense of Dark Arts professor after he began dabbling in Dark Arts but before he gained power, and Harry notes that he had already lost his good looks by then and was beginning to resemble the pale, snake-like creature he would fully become later on. Even many years before that when Tom Riddle was still pretty handsome, he was stated to have already begun to look a little pale by the time he took a job in a store to get hold of an ancient artifact.
James Potter and Sirius Black's young, teenage selves as seen in the 800-word prequel JK Rowling wrote for charity are completely interchangeable with Fred and George Weasley, who also go on to use the Marauder's Map (invented by James and Sirius and their friends), as well as one of them dying and leaving the other scarred for life. If you changed the names in the 800-word prequel, the story would fit exactly to Fred and George with the exception of physical descriptions, their dialogue has exactly the same patterns and brand of humour, making James and Sirius seem very shallow in development (at least, them in their youth.)
In the first book, there's a member of Dudley's gang named Piers Polkiss. From his description and what little we see of his personality, he's essentially an early version of Peter Pettigrew.
This is deliberate, if you look at his name. "Piers" is another form of Peter. "Polkiss" is Finnish; if you plug it into a translator, the meaning that comes up is "cycled around." Piers Polkiss is literally "Peter recycled."
Voldemort has shades of Adolf Hitler and Darth Sidious.
Probably of Dorian Gray, too; young Tom Riddle's attractiveness is very much emphasized by the characters and the narration; the more evil he commits, the uglier he becomes, and he has multiple soul jars, while Dorian had, well, a beauty jar.
Harry has been thought of one of Jesus Christ while Lily one of the Virgin Mary.
Extranormal Prison: Azkaban is a prison for evil wizards, guarded by the soul-sucking demetors.
Fainting: Many characters do this, but this unfortunately happens to Harry multiple times in each book, especially in Prisoner of Azkaban (wherein the Dementors inevitably have this effect on him) and Order of the Phoenix.
Done four times in the series: first, in the way some "pureblood" wizards look down on Muggles and those who have Muggles in their ancestry; second, in Hermione's well-meaning campaign on the behalf of house elves; third, the treatment of werewolves and "halfbreeds" such as Hagrid; and fourth, the Dursleys' bigotry against wizards. The second and third are part of a larger theme of non-humans being discriminated against, and centaurs fall into this category too; Dolores Umbridge hates them, and Firenze the centaur gets into trouble with his own people, who consider him an "Uncle Tom" and traitor for associating with humans. Lupin chooses to resign from school after everybody finds out he's a werewolf.
And the "official" wizard attitude to the other magical races is clearly portrayed as a different kind of racism to the Nazi-esque Death-Eaters, not open-minded egalitarianism; Harry is surprised to see a statue at the Ministry of Magic with a centaur and a goblin in submissive adoration of a wizard and witch; totally preposterous (unlike the house-elf in the same statue), but evidently the way the Ministry believes the world "should" work.
It is, perhaps, worth noting that the Ministry of Magic classifies all living creatures as either "beast" or "being", with the latter being less discriminated against. Centaurs are classed as "beasts", and thus discriminated against greatly... because they themselves discriminated, and weren't willing to share "being" classification with things like vampires. According to tie-in materials they were also insulted that humans thought they had authority in such matters at all, and originally insisted on the beast classification after the mermaid civilization was filed there for not speaking English (which was later rectified).
Draco Malfoy displays this often, calling Hermione a "mudblood" more than once (a slur for a wizard or witch that is born to non-magical, aka "Muggle" parents, who "purebloods" of certain persuasions, like the Malfoys, see as inferior) and such insults almost always end up badly for him, since the wizard m-word is as nasty as the muggle's n-word. Likewise with Snape whose life was ruined took a turn for the worse when he called Lily a "filthy little mudblood".
Hermione's campaign for house elves is portrayed as well-meaning but misguided, with her imposing human values on the elves and refusing to accept that the vast majority of them are actually happy with their jobs as long as they're not abused. She seems to have become better educated on the house-elf psyche by Harry Potter and the Deathly Hallows, though, and has gone for a more practical approach—at no point in book seven does she ask Harry to free Kreacher, but she does convince Harry to treat Kreacher well despite his betrayal in Harry Potter and the Order of the Phoenix. It pays off almost immediately, and again at the end of the novel.
In The Half Blood Prince, Tom Riddle murdered a woman for her artifacts and framed her House Elf for it. Dumbledore tells Harry that the Ministry should have investigated further but didn't "...because she was a House Elf". Harry had never sympathized with Hermione's campagin as much as he did at that moment.
There is also the treatment of Squibs (non-magic children of witches and iwzards). Even the Weasleys had a relative (Molly's second cousin) who possibly was a squib and, as such, an embarrassment to the family.
Fantastic Slurs: "Mudblood", a derogatory term for a witch or wizard who was born into a Muggle family. It's considered to be an extremely vulgar term as well, almost on par with the N-word; when Draco Malfoy first called Hermione this in Chamber of Secrets, there was a tremendous uproar and Ron even tried to curse him.
In Books 5 and 7, Snape's friendship and romantic hopes for something bigger are ruined when in reaction to Lily pulling an Embarassing Rescue, he says, "I don't need help from filthy little mudbloods like here." This ruined his life...to say the least.
Fantasy Counterpart Appliance: Mostly averted, because wizards either appropriate Muggle technology or invent something completely strange of their own, but there are a few cases, such as the Floo Network, which is regulated and functions not unlike a mass transit or communication system.
Fantasy Gun Control: Guns exist in the Muggle world, but apparently not even Squibs seem to have them in the Wizarding Community; in an article about Sirius Black, it's mentioned that the Muggles have been warned he's carrying a gun, which is then defined as "a type of metal wand that Muggles use to kill each other."
Justified - the series is set in Britain, where gun control is exceedingly strict!
Fantasy Kitchen Sink: Nearly everything about wizardry from Fantasy novels is revealed to exist — and every mythological creature as well, especially in Fantastic Beasts.
First Girl Wins: Ginny Weasley was the first young witch Harry heard at Platform 9 3/4, and Hermione was the first female friend Ron Weasley made. Years later, Harry married Ginny, and Ron married Hermione. In The Film of the Book, Ginny Weasley is the first girl Harry's age we meet in both the first film and the second. She's also almost the first girl we see in the third film — soon after Hermione's entrance, we see Ginny's face in a newspaper clipping.
Then there's the stories where Harry becomes "more intelligent". The most over-the-top example of this is probably Harry Potter and the Methods of Rationality, in which Harry mutates into a super-genius by having a professor for a stepfather, and several other characters also become vastly more intelligent because... they're wizards. Harry then uses his vast intellect to revolutionize magical research as a sort of wand-wielding Mighty Whitey.
There is at least one fic which states that Dumbledore slipped Harry and Ginny some potion to make them fall in love... and the epilogue is a delusion by Ginny, whom this potion brought to St. Mungos.
The Severus Snape fans tend to write stories that either ignore Deathly Hallows entirely, or simply the epilogue.
Let's not forget all the people Ret Conning Sirius' death after Order of the Phoenix.
This happens a lot, especially after Deathly Hallows, where the story seems to mostly fit into canon but where Snape, Fred or some other popular character is just inexplicably alive. It's not even a traditional "here's how they lived" sort of thing, they're just alive because the author didn't want them to be dead.
Flanderization: The Hogwarts Houses. Gryffindors are brave and righteous, Ravenclaws are clever and scholarly, Hufflepuffs are fair and sympathetic, and Slytherins are jerkasses. Okay, "ambitious and cunning" is the technical adjective for Slytherin, but let's face it: they're the house of bad guys, and pretty much nothing the books do as the series progresses addresses this issue. Slughorn and Snape are the only decent Slytherins ever named (even then Slughorn's the only actually nice one), and all the major antagonists except for Wormtail are either Slytherins or of unspecified house.
However, after the fall of the Death Eaters, Slytherin House isn't an "evil" house anymore, and they now accept Muggle-borns, but it still has a bad reputation.
Fluffy Tamer: Rubeus Hagrid. He has raised giant spiders, baby dragons, and a three headed dog. Their names were Aragog, Norbert, and Fluffy, respectively. He's a half-giant, so such creatures are less likely to hurt him, but he tends to not realize that most people aren't as indestructible as he is. This has landed him in trouble numerous times. Tom Riddle was able to use Aragog to frame him for opening the Chamber of Secrets and yet he never seems to learn. He's also a Fluffy breeder, credited with the creation of the Blast-Ended Skrewts, an incredibly dangerous and aggressive hybrid possessed of absolutely no useful qualities.
Fluffy the Terrible: Quite a few monsters, but the most famous is actually named Fluffy. Inverted with Hagrid's cowardly boar hound, Fang, and subverted in the case of his Acromantula, Aragog.
Flying Broomstick: Quite a few, often of plot significance, including the Nimbus and the Firebolt.
Rowling has admitted she wasn't the first to send kids to wizarding school. However, a lot of books have attempted to cash in on the success of Harry Potter, some of which even being obvious ripoffs.
However, an example that was actually a good thing was that the success of Harry Potter sent a few messages to authors and publishers — one, that a book for young-adults can still be enjoyed by an adult Periphery Demographic, and two, that kids actually do have the attention span to read a Doorstopper if they find the story interesting enough. To put it in perspective, books as long as some of the Harry Potter series in the childrens' section was almost completely unheard of. Now? You'll run into at least three.
For the Evulz: This seems to be the motivation behind at least half the things done by members of Slytherin House — especially Malfoy. Seems rather bizarre when you remember that they're supposedly the House for the cunning and ambitious.
Four-Temperament Ensemble: The Marauders seem to fit this — James is Choleric, Sirius is Sanguine, Remus is Phlegmatic, and Peter is Melancholic.
Alternatively, James is sanguine, Sirius is choleric, Remus is melancholic, and Peter is leukine.
Full-Name Basis: Harry Potter, to a few characters—notably Dobby and Voldemort.
Full Potential Upgrade: Wands are this for wizards. They have to either be precisely matched when purchased or legitimately won from a prior owner for best effect. Wizards who are shown to use hand-me-down wands (Ron and Neville) show a level of improvement when using one purchased just for them.
Functional Magic: JKR says in interviews that she spent time working out the limits of wizard magic, but the novels only touch on these a few times.
Funny Background Event: A common aspect of Rowling's writing in this series—one of her favorite kinds of scenes seems to be one where the characters are having a private conversation, while in the background something amusing is going on at the same time. Most commonly, in the school scenes these often involved Peeves.
Giant Squid: There's one in the Hogwarts lake. It's mainly there to add color and is very much a Gentle Giant - when Dennis Creevey falls in the lake, it helps him back in his boat. Lee and the twins are even seen tickling it at one point.
Good Cannot Comprehend Evil: Dumbledore has shown that he can understand quite bit about Voldemort. However, it turns out that Dumbledore was unable to figure out that Voldemort hid one of his Horcruxes in the Room of Requirement. Why? Because Dumbledore was a model student who never cheated and hence had no need to use the room. Harry, however, was certainly not a model student, he cheated a couple of times, and he used that room, so he could figure it out.
Happily Married: Molly and Arthur Weasley. While they were still alive, Harry's parents Lily and James counted too.
There's even reason to believe that Lucius and Narcissa Malfoy may fit this trope.
Vernon and Petunia as well, whatever else you can say about them.
Mr. and Mrs. Longbottom were likely this until they were driven insane by the Cruciatus Curse
Mr. and Mrs. Granger appear to be this, even though we don't see much of them.
Bill and Fleur. Harry and Ginny and Ron and Hermione end up as happy marriages, too.
Subverted in the case of Ron and Hermione according to Word of God.
Word of God has that Luna, Neville, George, Percy, and Dudley all were this as well.
Happiness in Slavery: Most house-elves love being servants. There's also the issue (which Hermione never seems to grasp in canon) is that with one exception, "freeing them" — especially from a master who isn't openly abusive — is equivalent to sacking them in disgrace. Of course, there are several instances of House Elves working around orders or finding loopholes to disobey masters that they don't like.
Even the exception to the rule, Dobby, essentially considers freedom the right to decide whose orders he will obey.
Hate Sink: Plenty of characters exist solely to inspire hatred in the reader, starting with the Dursleys and later including Rita Skeeter, Zacharias Smith, Cormac McLaggen, and Cornelius Fudge. But the ultimate example has to be Dolores Umbridge, a secondary villain whose every quality, including her name, is carefully designed to make the reader despise her as much as humanly possible.
His Own Worst Enemy: Although Harry is Voldemort's literal mortal enemy, Voldemort does have a huge responsibility on his own downfall right from the very beginning, when he was presented the Schrodinger's Prophecy he could've chosen to ignore, but didn't, and in doing so, created his own downfall with Harry's scar.
Homeschooled Kids: According to Word of God, this is the easiest way for wizarding families to get their kids through Primary School without exposing the wizarding world to Muggles. In Deathly Hallows it's also stated that wizarding parents have the option of homeschooling their children rather than sending them to Hogwarts or a foreign school, but at that point Voldemort's regime makes it mandatory for parents to send their children to Hogwarts so he can keep an eye on them.
Homoerotic Subtext: Intentionally invoked with Sirius and Lupin, according to Alfonso Cuarón. Apparently, the director thought that Lupin was a "gay junkie".
Hormone-Addled Teenager: Nicely averts this trope until the later books, and then subverts it by making the main characters' teenage relationship tangles A) realistic and B) quite secondary to the actual plot. Done especially well with Hermione. After her brief liaison with Viktor Krum in Goblet of Fire, she decides dating isn't all it's cracked up to be and realizes she's still not old enough for serious romantic entanglements. She's also largely uninterested in clothes and doesn't care that she has frizzy hair, concerning herself with academics rather than vanity.
Hufflepuff House: In addition to having the Trope Namer, the Ravenclaw House served as something of a less triumphant example of the trope, at least until Cho Chang and later Luna Lovegood began taking more active roles in the plot.
Hyperspace Is a Scary Place: A less extreme example with Portkeys, which accompany rather intense and blurry visuals. According to Pottermore, "Portkey-sickness" (hysterics and nausea) was a common start-of-school ailment during Hogwarts's brief flirtation with a Portkey network as subsidized transport to campus.
Apparition certainly counts, as Harry describes it as an extremely unpleasant sensation of being squeezed through a very tight tunnel.
Travelling by Floo powder could also count as a less-extreme example, considering that it involves spinning very fast and you could see any manner of things in one of the fireplaces, or fall out at the wrong grate, as Harry does in Chamber of Secrets.
Lord Voldemort and his Death Eaters are prejudiced against wizards with less than pure wizarding blood and non human magical creatures in general despite he himself having a muggle parent. While he's counting on the anti-Muggle feelings of his followers, he genuinely despises Muggles and anything he considers Mud-blood — and he apparently has a one drop rule for everyone except himself and personal Death Eaters like Snape. While they also recruited Giants and Werewolves, they probably rationalized them as second and third tier "citizens" in Voldemort's new England.
It was suggested a few times that he was exploiting the prejudices of his own followers more than enforcing his own, and that he really didn't care about anything but his own power anymore. Voldemort's own half-blood status was one of the reasons he started going after power. He considered his father to be lowly and weak and cowardly for turning away his mother and was determined to ignore his own history and go with wanting power.
And then we have Umbridge. Although fans have a lot of reasons to hate her with relish, her hypocrisy is certainly one of the main ones. In her introductory book, she is seen as an agent of the Ministry, sycophantic to its causes and forcing tyrannical laws onto the school in order to get her own way, yet at the same time, she gleefully (although secretly) engages in activities that are highly illegal and certainly unforgivable, even by the Ministry. Worse, she punishes Harry most severely for asserting that Voldemort is at large, insisting that he "not tell lies", while aping the official Ministry line on Voldemort, which is patently and obviously false. In the final book, she persecutes Muggle-borns for "stealing magic" which she should certainly know is a nonsensical charge, while claiming that the locket she took as a bribe is an old family heirloom supporting her own bloodline. The injustice and cruelty of this enrages Harry so much that he attacks her immediately without resorting to a more subtle plan.
Sirius, too, despite his axiom that the measure of a man is how he treats his inferiors, he behaves detestably towards Kreacher (since Kreacher reminds him of the house and the family he hated while growing up). Indeed, this is one of his least admirable qualities. It also bites him in the arse. Hard. But as Dumbledore clarifies, Sirius was kind to House Elves in general but Kreacher was special as a reminder of his home and the bad childhood that he hoped to escape.
Also, his belief that "the world isn't split into good people and Death Eaters" goes out the window during the argument with Snape. Though the latter is himself not blameless in that regard. Word of God admits that this is a serious flaw for Sirius, but she also admits that it's difficult to be morally consistent in life.
Lupin in the third book tells Harry that he's appalled that Harry never brought the Marauder's Map to a teacher's attention given how useful it would be to catch Sirius or how useful it'd be to Sirius if he found it. Yet Lupin never bothers telling Dumbledore (or anyone except Harry, Ron, and Hermione) that Sirius is an animagus and knows about the tunnel from the Shrieking Shack onto Hogwarts grounds.
I Am Big Boned: Madame Maxine uses this excuse not at the prospect of being called fat, but when Hagrid speculates that she is half giant. This trope also applies to the Dursleys blaming Dudley's weight on baby fat. In the Prisoner of Askaban PS2 game, an unnamed girl says this about the Fat Lady.
Idiot Hero: Played with. Harry is not stupid per se, but he is lacking in common sense on more than one occasion and often operates on instinct rather than thinking things through. He's often trying to take on wizards far older and far more experienced than him, he pins all of the wrongdoing in the school on Draco Malfoy (or Slytherin in general), and if ever he senses a corrupt and possibly harmful teacher, it's always Snape. It gets to the point where, in Half-Blood Prince, Ron and Hermione start rolling their eyes at Harry whenever he brings up his "Malfoy is a Death Eater"-theory. Of course, this is subverted when he turns out to be correct about both Malfoy (who is a Death Eater) and Snape (sort of). This gets him into trouble in Order of the Phoenix, and Hermione even lampshades this by telling Harry he's got "a saving-people thing" that Voldemort not only can exploit, but has exploited in the past. Namely, kidnapping a mind-raped Ginny and taking her into the Chamber of Secrets because he wanted to meet him.
Ill Girl: Ariana, Dumbledore's sister, became half-insane because she refused to use magic after a traumatic experience where she was attacked by three Muggle boys who found out she was a witch. Her family put it about that she just had poor physical health to avoid attracting attention, leading many people to theorize that she was a Squib, when in reality she would have magic exploding out of her when she couldn't keep it in anymore.
Just look at every pureblood family tree; Sirius's parents themselves were second cousins, and it is possible that Lucius and Narcissa are related, too, in some way or another.
Also, the Gaunts, heirs of Salazar Slytherin and Voldemort's family, were apelike and extremely stupid and unattractive. According to Rowling, this is due to generations of inbreeding (close inbreeding) to preserve not only their pureblood status but also their Parseltongue abilities. Handsome young Voldemort got all of his looks from his Muggle father.
Dumbledore: [The Gaunts] were known for a violent streak that flourished in the family, due to their habit of marrying their own cousins.
Inhumanly Beautiful Race: Veelas are beautiful women with long silver-blonde hair, blue eyes, shining skin and perfect teeth. Although they have supernatural powers to seduce men and hypnotize them so it is possible that Harry's description of them is a little exaggerated. They have one downside though: piss them off and they turn into crazy bird monsters that throw fire at you. Also, Fleur Delacour said she was part Veela on part of her Grandmother.
Ineffectual Death Threats: The staff of Hogwarts seem to love to toss around expulsion as if it's done weekly — especially directed at younger students. We only ever meet one person expelled from Hogwarts — Hagrid, who is now a professor.
Internalized Categorism: Some of the meanest persons are said to hate themselves because they are squibs — and taking this self-hatred out on young wizards of whom they are jealous. While more ambiguous, it is also possible that Tom Riddle (Voldemort) himself was embarrassed over being a half-blood and that his Fantastic Racism was partly a overcompensation for this. (This example is for the novels only, the movies don't have room for such nuances.)
Invincible Incompetent: Harry may be the highest-functioning version of this possible, given his constant victories despite rarely being noted as exceptionally gifted at any type of magic outside of Defense Against the Dark Arts and flying, and fully half the time defeating the villain either by accident or through the actions of another.
This is his main reason for refusing Hermione’s suggestion to teach Defence Against the Dark arts in Order of the Phoenix, he’s just very aware that he’s lived as long as he did thanks to situational luck, external help or some personal flash of inspiration that he can’t exactly teach others to have.
Ironic Echo: (Film version): "Sorry, Professor, I must not tell lies."
The series often displays many examples but the Half-Blood Prince is probably the one with the most and/or largest ones. In this book Snape stops teaching Potions class and teaches Defence Against the Dark Arts at Hogwarts and is replaced by Professor Slughorn. Previously Potions was Harry's worst subject because he hated Snape and never made the effort in class. In his first class with Slughorn he finds a second-hand book labelled as "the property of the Half-Blood Prince". Inside the book are vast amounts of hints that help Harry in his Potions classes, making it his best subject. Then the big reveal is that Snape is the Half Blood Prince. At one point in the book Harry even makes a throwaway remark that The Prince was a much better teacher than Snape. Dramatic irony at its finest.
The people who seem to care the least for Harry (Vernon, Petunia, Snape, Aberforth) are the people who sacrifice the most of their own security and commodity to keep him free from Voldemort.
Although everyone agrees that Professor Trelawney has not a whit of divinatory talent (most of the time), it happens that every single prediction she makes eventually comes true. Largely this is because they are extremely vague or already probable (for example, telling Harry, who's been marked as the nemesis of the Dark Lord, that he is in danger), but even so, her ultimate record is astoundingly perfect.
It Amused Me: The only reason Peeves the poltergeist does anything, although his pranks are (generally) more irritating than harmful. Dumbledore and the Bloody Baron are the only people who can control him.
Jerkass: If you had a penny for every character in this series that is a massive a-hole, you'd have pennies literally coming out of aforementioned a-hole.
Special mentions go to the Dursleys, the Malfoys, Snape, Zacharias Smith, Cormac McClaggen, Percy Weasley, Dolores Umbridge, and sadly, James Potter (from what we see in his youth during Snape's flashback).
Join or Die: Standard operating procedure for the Death Eaters.
Just Eat Gilligan: Cracked pointed out that asking the Muggles for help in taking down Voldemort would have solved a lot of problems. Note that at the higher levels of politics, Muggles and Wizards know of each other as vaguely allies, despite the widespread dismissal of Muggles as being weak.
Michael: We can shoot people with a thousand rockets... from space... with iPhones!
Karma Houdini: The Malfoys, who escape death and/or imprisonment due to their one redeeming quality—love and devotion to each other.
Kid Detective / Amateur Sleuth: The Power Trio. A big part of the books' structure (and their appeal) is that most of the plots are mysteries that Harry, Ron, and Hermione can solve ("What's hidden beneath the school?", "who is Slytherin's heir?", "who put Harry's name in the Goblet of Fire?", etc.), which is the main reason why three underage wizards can have any impact on the story at all.
Kill It with Fire: One of the few ways to destroy a Horcrux is with the dark magic spell Fiendfyre, a.k.a. cursed fire, but the spell is so dangerous and hard to control that even Hermione says she wouldn't have dared try it. And in Half-Blood Prince, it's demonstrated that the Inferi are, if not destroyed, at least repelled by fire.
Killed Off for Real: *deep breath* Cedric, Sirius, Amelia Bones, Emmeline Vance, Dumbledore, Hedwig, Mad-Eye, Ted Tonks, Wormtail, Dobby, Fred, Lupin, Tonks, Colin, Bellatrix Lestrange, Voldemort, and Snape.
Kudzu Plot: All of the Harry Potter books (except Harry Potter and the Deathly Hallows) end with some answers being revealed, but also leaves the reader asking several questions which will not be revealed until later books. Some questions that are asked in the first book aren't revealed until the last book. Thankfully, they are all resolved in the end.
La Résistance: Dumbledore's Army, Potterwatch, and the Order of the Phoenix.
Living Legend: The Boy Who Lived. You Know Who. Albus Percival Wulfric Brian Dumbledore.
Loads and Loads of Characters: Since it takes place at a boarding school and all. Let's see: The protagonist Power Trio, about a baker's dozen worth of significant classmates, the entire Potter and Weasley families, about a dozen teachers (two of which are hardly ever shown, admittedly), another dozen guys from the Ministry of Magic, and about half a dozen on the antagonist side. And that's just for starters...
Loose Lips: You can trust Rubeus Hagrid with your life, you can even trust him with underage children, but you can't trust him with your secrets, through no malice of his own. Goblet of Fire has Bertha Jorkins, whose only known attribute is this due to her chronic tendency to gossip — to her own cost.
Loves the Sound of Screaming: Filch loves torturing misbehaving children, and misses the old days when he could hang kids from the rafters and hear them scream. A lot of that talk is probably wishful thinking (not that this is a huge improvement); Dumbledore seems to have hired Filch, and Dumbledore most likely did not allow thumb screws, chains, or any of the other implements Filch claims to miss. His paraphernalia could easily be left over from well before his time.
Lucky Seven: Seven books, based on Harry's seven years in school. Seven Weasley children. Voldemort tries to split himself seven ways using himself + six horcruxes (it's the eighth one that screws him over). This is foreshadowed in The Movie with the rock broken into seven pieces in young Tom's room. In-universe, seven is stated to be a very powerful magical number.
Subverted by Voldemort. Despite having a legion of followers who seem utterly loyal, he is betrayed a few times by people who, despite being Slytherins, start to hate him for various reasons. Snape, for example, betrayed him for over a decade; Regulus was willing to die to stop him; and Narcissa lied to him to protect her son. Not to mention that he created his own worst enemy in Harry when he tried to kill him. Voldy clearly missed the part about "avoiding hatred".
Played with by Dumbledore, whose philosophy of love and trust clashes with a number of his actions that are very manipulative indeed. His manipulation often does more harm than good, and Dumbledore acknowledges this, such as at the end of the fifth book.
Made of Indestructium: Implied of the Deathly Hallows. The Invisibility Cloak’s flawless state despite its ancient age is the first clue to its true nature, the same strike that destroyed the Horcrux within the Resurrection Stone did nothing to impede its function as a Hallow and the fact that the Elder Wand survived through the ages despite being constantly in the centre of violent conflicts all point to this.
Any such implications are completely ignored in the films, where Harry effortlessly snaps the Elder Wand in half.
Magic A Is Magic A: Followed fairly closely, mainly with the teleporting power; the reader is repeatedly told that it's impossible to teleport in or out of Hogwarts. In Book 7, we find out why this is perfectly in line with the rules. In Film 6, when Harry reminds him he's about to do something impossible, Dumbledore states "This is one of the benefits of being me."
It's also explained, when they're doing their Apparition test, that the room in which they're practising has temporarily had the blocking field suspended—but they're warned not to try it after the lesson's over.
Magical Camera: Photographs and paintings alike are animate and semisentient, due to some kind of special darkroom process.
Magic Carpet: These are banned in Britain, since they're defined as a Muggle artifact by the Registry of Proscribed Magical Objects, though they're apparently used by wizards in other countries.
Magic Hat: The Room of Requirement turns into whatever people need. For a more literal magic hat, there's the Sorting Hat, from which the Sword of Gryffindor can be pulled by a true Gryffindor.
Magic Map: The Marauder's Map, showing everything and everyone on the Hogwarts grounds.
Magic Versus Science: Electronics don't even work around Hogwarts, wizards are disdainful of Muggle technology, and most Muggles have no idea magic exists. Interestingly, while wizards can do most things much more quickly and efficiently with magic, there are a few cases where the wizard method just sucks compared to the Muggle method—most notably communication, where the wizards have nothing as effective as (albeit then-primitive) cell phones or Internet. They send letters by owl, which is better than the postal service, but nowhere near as good as an email (and subject to getting owlnapped/eaten on the way). The closest thing they have to a phone is sticking your head in a magic fireplace, which is not portable like a cell phone.
Subverted by one Arthur Weasley, who seems to be one of the few (along with Hermione, who was brought up in the Muggle world) who sees the usefulness of taking common Muggle inventions then enhancing them further with magic. Everyone else just thinks he's eccentric.
Much of this is clearly intended to reflect the cultural differences between those who live entirely in Wizarding society and those who mingle in both. For example, by the end of the series Ron, who is now married to Hermione, a Muggle-born, has gotten a driver's license. However, a cultural bias can also develop in young wizards and witches since electronics do not work in Hogwarts, which is where they will spend a large chunk of their childhoods. Thus, even Muggle-borns who grow up in regular society may become distanced from it as they live for years with magic as the only "technology" available to them.
There is also a legitimate question as to what is "magic" and what is "science". In the book Harry Potter and Philosophy, one contributor, Gareth B. Matthews, observes:
Matthews: "The natural assumption is that any subject that can be taught to students in such a way that their competence in this subject can tested by examination is a science."
This is further illustrated by the fact that it is frequently shown that magic, much like science, operates under comprehensible laws and that if performed correctly will produce a predictable result. If performed incorrectly (something often the shown in the series) it will likewise produce the incorrect result. This is most explicitly demonstrated in the subject of Potions, where in Harry Potter and the Philosopher's Stone Professor Snape states it unequivocally:
Snape: "You are here to learn the subtle science and exact art of potion-making. As there is little foolish wand-waving here, many of you will hardly believe this is magic."
Mama Bear: Several, and they seem to be the bane of Voldemort's existence. Twice he's been undone by a mother trying to protect her son. The first, of course, was Lily sacrificing herself for Harry, and the second was Narcissa Malfoy, who lied to him about Harry being dead for the chance to save Draco.
And McGonagall, who really shines near the end of Deathly Hallows.
Actually, the fact that Mama Bears were the bane of Voldemort is actually tragic in a way, since his own mother gave up on him and died, which probably screwed up his life in the manner that led to his genocidal tendencies.
Master Race: Many pureblood families of wizards view themselves this way; Voldemort, whose reasons for hating muggles are much more personal in nature, plays on this to attract followers.
Meaningful Name: And how. Indeed, certain characters "just happen" to have names that relate to what they are, to the point of providing more astute readers with a possible spoiler.
As an example, if you hated Dolores Umbridge, well, guess what? The author wanted you to feel that way. Dolores comes from Spanish, and it means "pains". Umbridge is pronounced just like the word "umbrage" (ˈʌm.brɪdʒ), and it means "feeling of anger or annoyance caused by something offensive". What an apt name!
Remus Lupin: Romulus and Remus, twins who were raised by wolves; "lupine" = wolf-like. Asking for it.
Naturally, Sirius Black can turn into a black dog. His dog form is mistaken for a Grim, one of names for the Black Dog myth, which in some legends aids people (hint) but in many either brings or signals doom (ie. they have a bad reputation). Similarly, "dog days" were named because the appearance of Sirius in Egypt coincided with the flooding of the Nile. Aaand "black dog" also refers to depression. He really didn't have a chance.
Minerva is the Roman equivalent to the Athena, the Greek goddess of wisdom. Minerva McGonagall is pretty smart herself.
On the same note, Hermione is the female version of Hermes, the messenger of the gods of Olympus, and also the god of knowledge.
The Gaunts were a once powerful magical family, now reduced to squalor, while "gaunt" means lean and haggard.
Salazar Slytherin is associated with snakes, as his last name might suggest. And his first name may be a reference to Antonio Salazar, the Portuguese dictator.
Rowena Ravenclaw, and the house named after her, is associated with intelligence. The raven is one the smartest birds there is.
Luna Lovegood is a quite spacey and moony.
Arguably her last name as well, when you consider how much she values her friends.
"Malfoy" means "bad faith" in French.
"Alastor" roughly means "avenger" in Greek. Alastor Moody seeks and captures criminal wizards.
Memetic Badass: In-universe example. Rumours about the incredible (and possibly dark) powers that Harry possessed were circulating before he'd even arrived at Hogwarts. And the Power Trio were absolutely on the receiving end of this during Deathly Hallows, when the Wizarding World is hearing stories about three high school students who rescued prisoners from the headquarters of the Ministry of Magic itself, escaped Malfoy Manor (basically Death Eater HQ) from under the nose of Bellatrix Lestrange, broke into Gringotts and escaped by stealing the dragon(!!!), on top of regularly pwning Death Eaters and repeatedly escaping from right under Voldemort's... umm... slits.
Mind Probe: Legilimency is the art of probing into another person's head and reading their thoughts and emotions. It can be used in relatively harmless ways to detect lying and read surface thoughts, but deep searching can completely destroy the target's mind.
The mental link between Harry and Voldemort potentially allows a two-way channel for either one to search the other's mind. However, while Harry can, if willing, look inside Voldemort's mind with relative ease and end up only a few nasty headaches worse for wear, Voldemort can't reach too deeply into Harry's mind without suffering unspeakable pain. Dumbledore theorizes that attempting to touch Harry's soul with Voldemort's already-unstable fragmented one causes the latter to rip itself apart.
Mind Rape: What happens if you are arrested and sent to jail. Or get on the wrong side of a Legilimens.
Misery Builds Character: Implied to be the reason why Harry has more humility than his father had at the same age; growing up with his abusive Aunt and Uncle made him a better person. Though, this is carefully qualified since there are other cases where misery did not build character, namely the young Tom Riddle and Severus Snape who suffered bad childhoods and became jerkasses, with the latter undergoing Heel-Face Turn only after realizing he made a terrible mistake and even then not changing his genuinely unpleasant personality one bit.
Dumbledore himself notes that Harry is exceptional for coming out of his childhood with the capacity to love that he imbibed from the memory and sacrifice of his Good Parents. And Harry himself mocks this concept when he tells Remus off for trying to abandon his family under the misplaced idea that his children are better off without their werewolf Dad.
According to Word of God, this trope is why Dumbledore lets Snape get away with being such an asshole to his students. ("Dumbledore believes there are all sorts of lessons in life ... horrible teachers like Snape are one of them!"). Dumbledore is perhaps the biggest example, his youthful relationship with Grindelwald and the resulting death of his sister made him a lifelong atoner for an action he never forgave himself for.
Misfit Mobilization Moment: In Harry Potter and the Deathly Hallows, Kreacher leads the house-elves employed at Hogwarts into battle against the Death Eaters.
In Order of the Phoenix, Harry, Ron, and Hermione are already-mobilized misfits, but they're joined by Neville (who Took a Level in Badass); Ginny, who up to that point was nearly an extra and only Ron's little sister; and Luna, Hogwarts's own Cloudcuckoolander.
The whole final battle is this for the good guys: Order of the Phoenix, Dumbledore's Army, teachers and staff of Hogwarts, Grawp-the-giant, thestrals and hippogriffs, centaurs, house-elves, and probably others. Even the non-Junior Death Eater Slytherins led by Lovable Coward Slughorn.
Just think of a good guy who's still alive by this point in the story. Any good guy at all, no matter how obscure. They show up. note Okay, not some other very minor characters who get the shaft.
Harry and others are seen using the so-called Unforgivable Curses in the last book. This could be chalked up to being in a war, and using Unforgivable curses against Death Eaters was perfectly legal until in the previous war, when Barty Crouch Sr. published a writ of Outlawry against them. However, the Cruciatus curse (which causes mind-destroying pain) is used, despite it being less practical than either a killing curse or a simple stun.
The way even good wizards like Arthur Weasley regard Muggles. Most wizards and witches (if they aren't Muggleborn) range from outright violence (on the Death Eater end) to a sort of paternalistic condescension (such as Arthur's case). And you can't help but be a little disturbed by the willingness to use things like Memory Charms on them to uphold The Masquerade (especially after seeing what a really strong one did to Lockhart). Not to mention there was a war going on where they were the targets and even the Prime Minister was kept almost entirely in the dark.
Moral Guardians: The seemingly endless parade of whackos who insist that the books entice children into the occult and devil worship.
Moustache de Plume: "J.K. Rowling" is a pseudonym forced upon the author, Joanne Rowling, because her publisher feared that young boys (the target audience) wouldn't read books written by a woman. Rowling didn't even have a middle name by then, so she used her grandmother's name, "Kathleen", in the pseudonym.
Names to Run Away From Really Fast: Voldemort (you know he's bad when most people are afraid to even say his name). Draco and Lucius Malfoy, Dolores Umbridge, all of which are every bit as nasty as their names sound.
Also, Death Eaters, Dementors, and Acromantulas.
Narm: Plenty of it in-universe, since we see practically the whole series through Harry's point of view. It gets lampshaded whenever the Dursleys have an emotional moment, usually coupled with some variant of the phrase "Harry suppressed the urge to laugh."
“Frustration was running high and there was a certain amount of ill-feeling towards Wilkie Twycross and his three Ds, which had inspired a number of nicknames for him, the politest of which were Dog-breath and Dung-head.”
The Death Eaters believe in the superiority of pure blood, and will kill anyone they feel is inferior to them. Their leader, Voldemort, hates anyone not of pure wizard blood, yet he himself is not pure blood; Adolf Hitler viewed "Aryans," commonly portrayed as blonds with blue eyes as the master race, yet he himself was brown haired with brown eyes, and may have had a bit of Jewish ancestry. J.K. Rowling acknowledged the Death Eaters are supposed to represent the Nazis. In the fourth movie, they're also symbolized as Klansmen—check out the KKK-inspired headgear, torches and "burning signal".///
And that's not even getting into the ''seventh'' book, for most of which the Power Trio are on the run in one of the most blatant parallels of Nazi-occupied Europe ever seen. The Ministry of Magic has become so corrupted from the inside by Les Collaborateurs, that they essentially pass the Nuremberg Laws against Muggle-born wizards, and under the guidance of Umbridge are shown creating pamphlets touting purity of blood whose content and saccharine covers call to mind the publications of Julius Streicher. The various Death Eater minions inside the Ministry are dressed in khaki clothes, with red, white, and black armbands bearing the Dark Mark. The sign of the Deathly Hallows has a history very similar to that of the swastika, as well - originally an innocent symbol, then used by wizard-supremacist Grindelwald, etched on walls by stupid pricks to get attention...
Regardless, the possibility of a task force of wizards and muggles contributing to the Allied victory over the Nazis is invoked in-universe.
The Film of the Book of Deathly Hallows shows a snippet of Hermione's torture from the book, except instead of just hearing her disembodied screams, we also see Belatrix doing...something with the dagger in her hand to Hermione's arm. When we see her arm, we can see that Lestrange carved "Mudblood" into the inside of Hermione's forearm, much like how the Nazis tattooed numbers into the forearms of the Jews in concentration camps.
The effect of multiple magical curses/charms takes Harry about as near death as anyone can go without actually dying. Being the only person to ever survive the Killing Curse twice is actually part of what makes him famous in the wizarding world, causing many to refer to him as "The Boy Who Lived".
Voldemort also had a few, due to having a great magical insurance policy for awhile.
Never a Self-Made Woman: The most prominent examples being Molly Weasley and Lily Evans, but Tonks and Fleur fall into this too later on.
Nice Job Breaking It, Minor Character: At one point in Half Blood Prince, we see inside the memories of a Ministry official who was responsible for the arrest of a father and son who abused the daughter of the family, enabling her to go after the Muggle love of her life. All very well, right? Well, there's just one teensy-weensy problem — said daughter happens to go on to become the mother of the most evil and manical wizard this century. The Muggle love interest's name? Tom Riddle Sr.
...Which wouldn't have happened if Tom Riddle Sr. hadn't been such a jerk.
...Though said daughter effectively rapes him for months (by using a love potion on him). Not that Tom Riddle Sr. wasn't a jerk, mind, but he had reason to run.
And in the same book, we learn RAB stole a Plot Coupon and replaced it with a fake and a taunting note, which forces the main characters to find it again later because RAB didn't manage to destroy it. Especially annoying because of the circumstances of pointlessly gaining the fake.
No Eye in Magic: Some of the spells in the series are like this. For example, in Book 1, the main villain put a spell on Harry's broom during a Quidditch game, to make him fall off. Hermione stops the spell by creating a fire, which startles him into breaking eye contact with Harry.
In Chamber of Secrets, the basilisk can kill someone just by looking at them in the eye — fortunately, the only people we see who have encountered it manage to not quite look it in the eye: they see it in a reflection, or through a camera lens, or in a mirror, so it doesn't quite kill them.
There is also Legilimency, the ability to extract emotions and memories from a person's mind, which usually works via eye-to-eye contact. Dumbledore, Snape, and Voldemort are expert Legilimens, and scattered through the series (even before we knew what Legilimency was) we can find instances where Harry felt that they could "read his mind". Almost a "missed" example, but once or twice, Harry does look away from their gaze; initially, the reader would just assume he felt uncomfortable under scrutiny — now we know better.
No More Lies: Eventually, Dumbledore realizes that hiding the truth from Harry will only hurt him in the end and tells him about Voldemort, such as he knows.
No Ontological Inertia: Unless a spell is specified to be permanent, it will expire with the caster's death. (This apparently does not apply to permanent curse-caused physical or mental damage.)
Hogwarts is a rather dangerous place for kids. You would think that the parents would protest more often. But the only protests we ever see are when the Chamber of Secrets is opened and after a Wounded Gazelle Gambit by Malfoy in Prisoner of Azkaban.
In the usual course of things, there is only a little bit of danger (like the third corridor in our Power Trio's first year), but when it gets really bad (like when the Chamber of Secrets opens, or during book 6 when Voldy is back) parents yank their kids out of school. (Ironically, once Voldemort shows up in Hogwarts in person, he waxes philosophical about his love for the place and offers the students a chance to go unharmed.)
The Hogwarts potions class doesn't have fume hoods over the cauldrons, nor does it require that the students wear goggles while brewing.
"A safety measure failing? At Hogwarts? Will wonders never cease!" Kevin: So for this test [Goblet of Fire] they drowned four of their students? Mike:(chuckling) No no no. They simply tied them up and tossed them into the water, which breaks no laws I can think of.
The Department of Mysteries.
No Sense of Humor: Percy Weasley "wouldn't recognize a joke if it danced naked in front of him wearing Dobby's tea cozy." He does have a bit of a harshly sarcastic moment in Deathly Hallows, though, which is remarked upon with astonishment by his siblings.
Not Evil, Just Misunderstood: It's very easy to paint Snape as a 'bad guy' due to his personality and the ambiguity of what side he's on, but once you realize what he's been through in life, it's apparent that he isn't an evil character at all. (See Ambiguously Evil above.)
The Not So Harmless Punishment: Detentions at Hogwarts often involve dangerous tasks, such as searching for an injured unicorn (running into whatever hurt it, and possibly needing to deliver a Mercy Kill) in the Forbidden Forest. Then there's the Umbridge/Carrows version of detention, which involves Cold-Blooded Torture.
Sevens: seven years, seven novels, seven subjects (to start with), seven Horcruxes, seven players on a Quidditch team, Harry and Neville being born in the seventh month, seven Weasley children. The dedication for the seventh book is "split seven ways". The films take this further still; the number seven is on Harry's Quidditch robes.
Nine and three-quarters: Kings Cross platform; length of school year in months (Sept 1—late June); Harry's exile from the wizarding world in years (1 Nov 1981—31 July 1991)
Twelves: twelve subjects offered at Hogwarts (Charms, Transfiguration, History of Magic, Defense Against Dark Arts, Herbology, Potions, Astronomy; Care of Magical Creatures, Divination, Muggle Studies, Runes, Arithmancy), twelve-a-side in the Dept. of Mysteries. Twelve uses of dragon blood.
Primes: 17 sickles to the galleon, 29 knuts to the sickle. And of course all the sevens above.
Oddly Common Rarity: Hermione says there were only seven Animagi registered with the Ministry during the entire century, but the trio encounters three unregistered Animagi within two years.
And find out about a fourth, although he's been dead since the first chapter of the series.
Of course, three of the four mentioned above were close friends and undertook becoming Animagi together.
Offstage Villainy: We hear Neville's accounts of the abuse the Carrows have been dishing out to students during his seventh year, but never actually see any of it.
Speaking of Sadist Teachers, Dolores Umbridge, arguably the most evil non-Death Eater villain in the series, is seen threatening a few characters with the Cruciatus Curse and the Dementor's Kiss, but whether she ever actually subjects anyone to these things remains unknown.
Older Is Better: The series' best magicks and artifacts can generally be assumed to be ancient.
Only the Knowledgable May Pass: Gryffindors and Slytherins need a password to gain entry into their residences. Hufflepuff probably has similar security, we just never see it. Ravenclaw has a different arrangement, see the trope below.
And in the first book, the safeguard that Snape creates for the Philosopher's Stone entails solving a logic puzzle.
Operation Jealousy: Hermione attempts to do this in book six by asking Cormac McLaggen to Slughorn’s party to make Ron jealous, only to fail spectacularly as she can’t stand the guy’s presence for more than a minute. Ron’s relationship with Lavender had elements of this as well. Stuck in the crossfire of crappy decisions, Harry spends most of the conflict facepalming at both sides.
Our Liches Are Different: Voldemort is a pretty straightforward example. He split his soul into 7 pieces with successive murders, and stored each one inside a Horcrux. When his Killing Curse backfires and kills him, he remains stuck in the mortal world as "less than a ghost", yet unable to die. Eventually, one of his followers helps him to create a new body (although whatever he then becomes, it is doubtful it can truly be called human), and he gets back in business.
Panacea: The bezoar is an imperfect one. Unicorn blood will fix you at the cost of being cursed. Phoenix tears seem to work on anything with no catch.
Parental Substitute: The Dursleys are a bad version of this, even though they are the only ones who can truly protect Harry from Voldemort, because living with Petunia and Dudley—his only relatives who share his mother's blood—renews Lily's protection spell every year until Harry comes of age. The Weasleys, Sirius, and Lupin do a better job.
In Harry Potter and the Goblet of Fire, we learn that Voldemort murdered his father and grandparents as soon as he discovered they were Muggles, and not the Wizards he imagined. And that his father abandoned him and his mother while she was pregnant.
At the end of the same book, we learn that Barty Crouch Jr. murdered his father. Then transfigured his body into a bone and buried it.]] Barty makes much of how both he and Voldemort had very disappointing fathers and the pleasure of killing those fathers. He also seems to regard Voldemort as a father substitute.
The power of hate is explicitly said to be why Dumbledore is considered weaker (technically) than Voldemort. Voldemort, being fueled by hate, is willing to use evil magic like horcruxes or curses. Dumbledore doesn't because he's still sane enough to realize the cost of such power.
The first time Harry attempts an Unforgivable Curse against Bellatrix Lestrange, she brushes it off fairly quickly and tells him that righteous anger won't fuel an Unforgivable as well as genuine malice.
This is also what drove Sirius Black out of Azkaban. Dementors could take out happiness, but hate gave him direction while knowing that he was innocent kept him sane.
The Power of Love: alluded to throughout the series. It can protect a loved one from deadly curses and block mental magic.
Plot Induced Illness: The Weasley twins develop a range of sweets that make one ill and test them on fellow students. Hermione is unamused and shuts them down. Well tries to, anyway.
Police Are Useless: The Ministry of Magic proves to be very ineffectual throughout the entire series, and often get in the way of the heroes. This is exemplified best when Voldemort returns and they refuse to acknowledge that he's back, instead choosing to antagonize Harry and Hogwarts. Voldemort even keeps them around because they are more helpful than detrimental to him.
Portal Cut: Apparition done badly results in "splinching." This is where a person attempts to teleport, but leaves a part of themselves behind. Not in a comical bloodless way, but in a "neatly sliced off" kind of way. Wizard healing is such that these kinds of injuries are curable within a day or two, but that leads to splinching being played almost as light comedy — until it happens to one of the main characters.
An alternate interpretation of the declaration to hand Harry over to Voldemort in the last novel is that they are simply pointing out that there is no sense in everyone dying in order to protect Harry, when he's the only thing that Voldemort actually cares about.
The Slytherins all left before the final battle. However we later find out that a signifcant number of them lead by Slughorn actually did this in order to reach Hogsmeade and raise the alarm, before coming back with reinforcements.
Pre Meeting: In the first five books, Harry always meets (or at least hears about) his new Defense against the Dark Arts teacher before school starts. And he already knew the sixth.
She only made two real predictions, though, which makes it hilarious when even her random mystical BS turns out to be true (like Lavender's rabbit dying, a student leaving her class, or Umbridge being in great danger). She's also always predicting Harry's early demise. Nobody ever believes her. He dies in Book 7 at age 17. He does come back to life, of course.
Prophetic Names: Quite a few of the characters' names reflect some gained personality quirk or their adult job description, but no one ever remarks on this oddity. The allusions range from the blindingly obvious (a werewolf named Remus "lupine" Lupin) to the Genius Bonus worthy (Voldemort's ruthless female fighter and lieutenant is named Bellatrix "the Amazon warrior star" Lestrange).
Randomly Gifted: Being a wizard can run in families, but also manifests to muggles and magicless squibs can be born to wizards.
Rapid Hair Growth: At one point during his childhood, Harry's aunt cut off his bangs, almost shaving him except for the part that hides his scar. It looked ridiculous, but magically grew back before Harry's next school day. Justified because, well, A Wizard Did It (albeit unknowingly).
Really 700 Years Old: Wizards live longer than Muggles. (Although members of the Black family seem to die relatively young.)
It's implied that there are so few pure-blood wizards left that keeping the pure-blood line alive might have required some inbreeding somewhere along the line. That might have shortened the lifespan a bit.
Retcon: There are several details in the earlier books that were conspicuously changed for the later books; presumably, Rowling hadn't thought up certain events that far in advance.
Renowned Selective Mentor: Harry has a much closer relationship with the headmaster, Dumbledore, than is usual for a student, to the point of the Professor being almost a surrogate father. In the sixth book Dumbledore even gives him special lessons.
Reptiles Are Abhorrent: A snake is the motif for Slytherin House, the unpopular, "evil" house at Hogwarts, and for the Death Eaters. In Book 2, Harry fights a giant venomous snake. And Voldemort has obvious reptilian features and a Right Hand Attack Snake named Nagini, who goes out to do his dirty work and is one of his spirit vessels. Speaking Parseltongue is considered a mark of the Dark Arts. The only time snakes were ever portrayed in a truly sympathetic light was the incident with the harassed boa constrictor in Book 1. However, after the fall of the Death Eaters, the snake is no longer an evil motif and plays the same role of symbolism for Slytherin House as the lion, eagle and badger do for the other houses.
Harry and Ron never bothering to read Hogwarts: A History and Hermione's indignant responses.
Hermione figuring something out and running off to deal with it without adequately explaining to Harry and Ron what's going on, and Ron's indignant response (usually a Lampshade Hanging).
Hermione running off to the library in general, which gets tons of lampshades and humorous references in the later books even when she's not actually doing it.
The Dursleys humorously coming off worst when interacting with wizards, not that they don't deserve it. Becomes not-so-funny in and after the fifth book, though Dumbledore has a bit of fun with them before getting serious in the sixth.
Harry having incredibly ridiculous dreams, with different aspects of his life zanily mashed together in one absurd package, which he naturally never remembers when he wakes up. Leads to Mood Whiplash in the fifth book when one such dream suddenly segues into a terrifying vision.
Ron unintentionally offending Nearly Headless Nick with some tactless remark during the feast at the beginning of every year. Nick lampshades it in Half Blood Prince.
When the discussion is about Snape, and it involves adults and Harry, expect Harry to call him Snape, and the adult to respond with "Professor Snape."
Tiny Professor Flitwick seems to get knocked down and/or tossed across a classroom by a student's miscast Charm roughly once a book.
After the introduction of Luna Lovegood, fictitious beasts called crumple-horned snorkacks become one. Luna really believes in the existence of these creatures because her dad is the publisher of The Quibbler, a satirical tabloid that regularly publishes stories about the non-existent creatures. Other characters regularly joke about this, and Luna herself gets defensive, claiming they actually do exist. Oddly enough, this actually gets subverted in the seventh book, when a character comments that there wasn't any mention of the creatures in the latest issue of the magazine, because Luna's dad is publishing real stories about the resistance now.
Sadist Teacher: Snape, Umbridge, and the Carrows, in order of severity.
To Rowling's credit, there's hardly any of this in the entire series. There is, however, one rather egregious example...
"We're not going to use magic?" Ron ejaculated loudly.
Another time, Slughorn ejaculated.
School Saved My Life: Hermione pulls one of these in nearly every book. The other characters too, to a lesser extent.
The Scottish Trope: Subverted by Dumbledore and several other heroic characters who very determinedly say "Voldemort" despite the name's emotional baggage — and by Harry, who just doesn't have that baggage. The seventh book simultaneously double subverts, deconstructs, and perhaps reconstructs it, as He Who Must Not Be Named creates an enchantment that allows him to locate anyone who dares say his name.
Also, the Harry Potter Encyclopedia that JKR promised to eventually write is sometimes called "The Scottish Book."
Screw the Rules, I'm Doing What's Right: It's the Harry Potter Drinking Game! Take a drink every time Harry breaks one of the Hogwarts school rules. You'll die of alcohol poisoning three books in!
Hermione at first disapproved of Harry's and Ron's constant rule-breaking, but due to Character Development she became as disregarding to the rules as the boys are.
Fred and George usually break the rules because they just don't care, but one final (and spectacular) example of doing what's right is when they set off the fireworks and leave the school on their broomsticks to oppose the horrible Umbridge. The teachers don't even try to stop them. On the contrary, they encourage it because they all hate that old hag so much. Professor Flitwick even keeps a magical bog the twins conjure in the castle as a roped-off area because it was such a brilliant piece of magic.
Also in the same volume, Tom Riddle's diary has the "memory" of the teenage Voldemort sealed inside, which Ginny unknowingly awakens through her liberal use of the diary.
In Harry Potter and the Deathly Hallows, it's implied that Voldemort's final fate is to remain in a sort of limbo (specifically, the netherworld where Harry met Dumbledore after he died) forever, incapable of harming anyone ever again.
See the Invisible: There are several ways in which Invisibility Cloaks can be thwarted. The ability of dementors to sense people is not impaired by invisibility cloaks. Moody's magical eye can see through invisibility cloaks. A person wearing an invisibility cloak still shows up on the Marauder's Map. Animals with acute senses, like cats and snakes, can detect the person under the cloak. There are also some mundane constraints, such as the fact that the wearer remains solid, remains capable of making noise, etc.
Some fans simply didn't want to hear it, but things were still sufficiently fluid up to the end of Book Five to argue the point. Past book six, there was really no excuse. Ironically, the fear that this statement is a lie is used in canon by the Locket Horcrux to try to turn Ron against Harry.
In Book 7, Harry says that he sees Hermione as a sibling, but he doesn't love her in the romantic sense.
The fact that the visitor's entrance to the Ministry is an old broken telephone booth with the phone that should not work being located in a garbage dump is one to the pilot of Doctor Who, where Ian and Barbara find an old, broken police telephone booth with a phone that should not work in the Foreman garbage dump.
Redwall has a line about a rat named Wormtail losing a paw. Possibly coincidental, as the resemblance of a rat's tail to a worm is easy to come up with.
Significant Anagram: "Tom Marvolo Riddle" <-> "I am Lord Voldemort". Other languages revise the anagram to make sense in their tongues — or change his birth-name.
For example, in French: Tom Elvis Jedusor = Je suis Voldemort. "Jedusor" sounds like jeu de sort, meaning "gamble" or "lottery" — and Elvis is not really dead. And in Spanish: Tom Sorvolo Ryddle = Soy Lord Voldemort.
And in German: Tom Vorlost Riddle = Ist Lord Voldemort, which does not mean "I am Lord Voldemort", but "Is Lord Voldemort".
In the Greek translation: Άντον Μόρβολ Χέρτ = 'Άρχων Βόλντεμορτ' (Anton Morvol Hert = Archon Voldemort). 'Anton' doesn't have any particular significance, neither does 'Hert'—it gives the impression that they were just made up out of the spare letters. 'Archon', in case you're wondering, is an archaic word meaning "ruler" or "lord", though the term 'Λόρδος', the more commonly used word for "lord", is used throughout the rest of the translated text. It's noteworthy that they messed up the anagram, even so. The greek alphabet has two forms of O, omikron (o) and omega (ω), and one of the omikrons apparently transforms into an omega during the switch.
In Turkish the translators just added a "d" to Marvolo, turning the name into "Tom Marvoldo Riddle", so that the anagram could simply be "Adım Lord Voldemort", which means "My name is Lord Voldemort" in Turkish. Guess they were kinda lucky.
The Danish translation is one of the few that doesn't keep his first name as Tom, initially translating his name into "Romeo G. Detlev Jr."—"jeg er Voldemort". Later, it's revealed that "G" stands for "Gåde" which means "riddle" so at least they got that part right. They do keep his father's name as Tom, though, and explains that Merope used to call Tom Riddle her "Romeo". Detlev is a non-existing name that is very similar to "Ditlev", a Danish boy's name. (Which also just happens to be the Danish version of "Dudley".)
Dutch changes his name to "Marten Asmodom Vilijn" - no Tom here either - going to "Mijn naam is Voldemort" (My name is Voldemort) - no Lord title. The barman of the Leaky Cauldron is still called Tom, so when the same name issue comes up in book six, it is solved by Dumbledore telling the barman will be able to remember "Marten" because it is a common name.
The Norwegian: Tom Dredolo Venster, of which the surname means "left", so it is still a meaningful name. The "translated" anagram is "Voldemort den Store", meaning "Voldemort the Great".
Created a meta-text flurry during the sixth book, when a locket signed by "R.A.B." became important to the plot. One of the first guesses on this mystery character's identity was Sirius Black's brother Regulus. Those who read the books in foreign languages noticed that whatever Sirius's surname was changed to (i.e., that language's word for "black"), R.A.B's last initial had followed suit.
The translators allegedly had to figure this out for themselves.
The Chinese translation made do with a footnote (as always).
Silver Has Mystic Powers: Goblin-wrought silver is nigh-invulnerable, and can absorb the properties of what it pierces in order to make itself stronger. It's unclear how the goblins make it this way, or whether it's truly silver or simply called so because the same colour. There are many other objects in the series which are made of silver (the Pensieve) or have the appearance of silver (unicorn blood).
Single Woman Seeks Good Man: Hermione and Ron most prominently, but it seems to be a trend for non-villainous female characters: Molly Weasley, Ginny Weasley, Cho Chang, and resident babe Fleur Delacour are all very hot for good guys while the "bad boys" seem barely a blip on their radars. Lily Potter is debatable, given that James Potter is remembered as a Loveable Rogue by some people and a complete Jerkass by others; but all the characters note that James had to clean himself up considerably before Lily would condescend to so much as look at him.
Sliding Scale of Continuity: The first three books' storylines don't directly depend on the stories of the previous books; they each explain basic premises like the wizarding world, Voldemort, Harry's backstory, etc., Harry continues to live at the Dursleys', go to Hogwarts every year, have friends named Ron and Hermione, etc., and the actual events of the first two books don't matter by the third. The rest of the series, well...
Spanner in the Works: Voldemort and Dumbledore's decades long Gambit Pileup often gets messed up thanks to an intricate series of decisions and minor hiccups that sends their Rube Goldberg-esque device careening. A theme in the series is choice, and ultimately, for better and worse, every big and minor choice made by characters ends up making a difference, in ways nobody can predict.
The Elder Wand is apparently created to be this, as noted by Dumbledore in his notes in The Tales of Beedle the Bard, since despite being "an unbeatable wand", it is routinely defeated and passes over through the centuries. When Dumbledore acquired it, he hoped to die undefeated which he would have had Snape killed him as per their Thanatos Gambit. Instead Draco beats him without knowing what he's doing. Then to top this, Harry simply yoinks the wand out of Draco's hands and this ended up, giving him the advantage to defeat Voldemort.
The backstory, specifically the night James and Lily were murdered and Harry survived the killing curse is an even more tangled one, with tiny bits and pieces of information accumulated over the seven books. To sum it up, Severus Snape asks Voldemort to spare Lily, and Voldemort goes ahead with it. He tells Lily to "step aside" but she refuses, this creates a binding magical contract which essentially bartered Lily's sacrifice for Harry's life. When Voldemort went ahead and tried to kill Harry anyway, the curse backfired on him.
Actually addressed in-universe in a rather amusing way. The full list of rules for Quidditch is kept secret by the international leagues to prevent players from being tempted to break them.
Stalking Is Funny If It Is Female After Male: Magical date rape drugs are sold out in the open  and it's considered wacky hijinks when Ron gets dosed by a crazy fangirl. Harry, at least, doesn't find the prospect of love potions funny—at one point, he actually compares them to Dark magic.
Platform 9¾, a secret entrance at King's Cross station between platforms nine and ten.
The Room of Requirement.
Strictly Formula: The first three books play this fairly straight - Dursleys, Diagon Alley, Hogwarts, Quidditch, Christmas, the big plot issue, end of year feast, everyone goes home. Some formula stays for the later books ( Harry always starts out at the Dursleys in the books, no matter what) but Rowling then breaks these down as the universe gets darker and more complicated - and Harry matures.
In ''Deathly Hallows'' the fact that these youth are used to the formula of three large meals a day and adults looking over them gets yanked out from under their feet.
This is the result if the Killing Curse (Avada Kedavra) hits an inanimate object instead of its intended target, it will explode.
Played for laughs in the sports sections. Making fun at the fact that Americans Hate Soccer, they have an alternate sport to the popular wizard-esque football Quidditch: Quodpot, in which the players try to catch an explosive quaffle and not let it fall down.
Up until Harry Potter finds out the actual name of the creatures that guard Azkaban, a wizarding prison, everyone refers to them as "The Azkaban Guards." After he experience their happiness-draining power and is told their name, Dementors, in Prisoner of Azkaban no one refers to them as the Azkaban Guards ever again.
A meta example: Word of God statements had long established that Hermione's middle name was "Jane," which the fifth book also established as Umbridge's middle name. Perhaps invoking the One Steve Limit, the final book makes Hermione's middle name "Jean" instead.
Summon to Hand: The spell Accio. Brooms also rise into a wizard's hand when commanded properly.
Superpowerful Genetics: Magical ability seems to be mostly inherited, though there are exceptions in both directions (meaning that, under the laws of Mendelian genetics, it can't be determined by a single gene; Word of God has also hinted that the gift of magic preserves itself somehow).
Take That: Both Aunt Marge in Book 3 and Dolores Umbridge in Books 5-7 are thinly veiled expies of Margaret Thatcher, whom J. K. Rowling had a dislike for.
Many of the early memories of Voldemort viewed in Book 6 are meant to refute the assertions by some fans that Voldemort is really a woobie with a Freudian Excuse. In fact, he was an irredeemable Creepy Child who made everyone's lives miserable for no reason.
The romance subplot in Book 6 is basically one big Take That at the Harry/Hermione shippers. First J. K. Rowling gets their hopes up by getting Ron and Hermione into an argument and then pairing Ron with Lavender Brown. Then she cruelly dashes their high-raised hopes when Ron dumps Lavender and Harry falls in love with Ginny.
An argument between Ginny and her older twin brothers about the grand total of two non-Harry boys she'd dated can be taken as a slight against the "Ginny is a slut" shippers.
The MuggleNet book Harry Potter Should Have Died pokes fun at the whole shipping issue by entertaining the idea that Hermione decides to leave Ron after he reaches his mid-life crisis and have an affair with Harry.
Teach Me How To Fight: Dumbledore's Army is born when Ron and Hermione ask Harry to teach them how to use advanced defensive magic.
Technology Marches On: As with the majority of books (being minor - when no one cares when and where they are released) as Pottermania picked up steam in America but books two and three weren't available yet, people realized this new-fangled Internet thing could be put to good use and simply ordered the books directly from Amazon.com.uk. American Amazon.com cried foul - this was taking potential profits from them - but Amazon UK pointed out that this was simply the inverse of what usually happened - books were usually released in the USA first and UK readers would order directly from them.
Teen Genius: Hermione and Luna. They have the same level of intelligence, but they think in different ways.
It's implied that all of The Marauders, save for Peter Pettigrew, were brilliant students in their day. Dumbledore, Snape, Voldemort and Grindelwald were all profoundly gifted students in their Hogwarts years as well.
According to Horace Slughorn, Lily Potter (Evans in the day) was very talented, although not as much as James. She was particularly adept at Potions.
Harry is pretty smart, and he's highly competent in every field of magic, but he excels at Defensive magic. According to Word of God, he's even better at it than Hermione is and he could easily beat her in a duel. Not like they'd want to duel in the first place, anyway.
The first we are introduced to is the Floo network, which connects fireplaces magically.
The second is Portkeys, where a seemingly innocuous object such as an old boot — although it could be anything — teleports anything that is touching it at the right moment. These are usually timed precisely so that a user has to reach it by a certain point, otherwise it teleports without them.
The third is Apparition, which is mentioned by name long before the characters use it themselves — this is where a wizard/witch teleports of their own volition to anywhere they wish. One has to pass an Apparition test at the age of 17, making it a close analogue of driving. There are also many places where one cannot Apparate, including Hogwarts.
There are a small number of other methods; notably, the Vanishing Cabinets, which allow access to Hogwarts by Death Eaters in Book 6. House-elves are also able to Apparate where wizards can't.
The Government can track and limit use of the Floo network; this becomes especially relevant in Deathly Hallows after Voldemort takes control of it.
Apparition can't be used in Hogwarts. It's also dangerous: you might leave body parts at your starting point.
Tell Me About My Father: For both parents. The emphasis starts with Harry's father (except for his eyes; he has his mother's eyes). However we later find that Harry's father was a bit of an idiot as a teenager (though he grew out of it), and the focus turns more and more to his mother. Dumbledore mentions that his true nature is much more like hers, though he's inherited his diehard loyalty to his friends from his father.
Tempting Fate: "If I'd died as many times as she said I would, I'd be a medical miracle." Guess what happens in book seven.
The Four Loves: most of the good side characters show, in one or the other way, this trope. Harry is an example of the four types of love.
Storge: Towards most of the Weasleys and Hermione.
Phileo: Towards Ron and Hermione.
Eros: Towards Ginny.
Agape: Towards everyone.
The Chessmaster: Dumbledore, hands down. Even at the cost of his own life, and at the cost of the lives of several other characters, he outmaneuvers Voldemort quite handily through a series of very craft moves, even after his death, and eventually brings about his downfall without really needing to lift a finger himself. There's a reason he was the only one Voldemort ever feared.
Theme Naming: Not just the characters (most notably, everyone in the Black family is named after a celestial object, with the exception of Narcissa; and even Narcissa's son and grandson are named after constellations); there's also Diagon Alley and Knockturn Alley, which are puns.
Due to his megalomania, Voldemort occasionally refers to himself in the third-person, though this may be done intentionally to scare his victims or to sound condescending to establish authority over them (in the same way that a parent would call themselves "mommy" or "daddy" when talking to a child).
This Is Gonna Suck: The Trio in the first couple books when they get busted and sometimes almost expelled for breaking various rules, such as being out of bed after hours or flying a car to Hogwarts.
Prisoner of Azkaban began it with Harry learning a complex piece of magic, and then it got momentum in Goblet of Fire when Harry uses his copious free time (and help from Hermione) to pick up a variety of offensive and defensive spells.
Translation Convention: In-universe example. Parseltongue sounds like any regular language to those with the innate talent to speak it. This becomes an important plot point in the second book, and facilitates Nagini's ambush on Harry in the seventh.
Tragic Dropout: Dumbledore was orphaned in his teens, and was forced to give up many of his ambitions in order to become the new patriarch of his family and care for his younger siblings.
Trapped In Villainy: Draco Malfoy who, for the first five books, is just a nuisance for Harry to deal with at school. Once he joins the Death Eaters, however, things change. He's given the job to kill Dumbledore, which seems simple enough in theory. But once Draco realizes that he can't follow through with murder, he remains hesitant throughout the next book, and only stays in Voldemort's service because he's terrified of the man.
Ultimate Job Security: Ignoring the fact that Hogwarts remains in operation despite having a running body count, Argus Filch is an exceedingly bitter man who explicitly enjoys causing students pain because he's jealous that they're learning magic while he's incapable of using it. At no point is the idea of firing him ever entertained.
Unicorns Are Sacred: Killing a unicorn is seen as a particularly heinous thing to do; Firenze refers to it as a "monsterous thing". The only person known to have done it in the series is Voldemort/Quirrel, further emphasising this. Drinking unicorn blood can prolong one's life, but the drinker will be cursed from the moment the blood touches their lips for having slain "something so pure and defenceless".
Unnecessary Roughness: Quidditch. Dear God, Quidditch. It has two lead balls which are magically enchanted to bash people senseless.
Unstoppable Mailman: The owls will find you to deliver a letter, no matter where you are. Even if you don't want the letters. And they know if you've destroyed them without reading them (as the Dursleys are very displeased to find out.)
Unusual Euphemism: Several, most notably the term Mudblood, which, in the wizarding world, is just as bad as saying the n-word in Real Life.
Blood Traitor = a pure-blood wizard who supports Muggles.
Unwitting Pawn: Pretty much the entire wizarding population other than Dumbledore, Snape, and Voldemort.
Snape may be a knowing pawn, but even then, there are things he is kept in the dark about.
Arithmancy. Although, since we never learn anything about arithmancy, it's entirely possible that it could be an accurate use of the "-mancy" suffix (if numbers are being used to divine the future, for example). Traditional divination is treated like the magical equivalent of a psuedoscience in-universe, so arithmancy might be a more 'scientific', if less fun, alternative.
Played straight in the Spanish translation. Occlumency is translated as "Oclumancia", which would implicate some kind of... hidden divination? It should have been Oclumencia instead (the -mens, -mency suffix implying "mind" is correctly used in English and should have been carried on in the translation as -mencia).
What Beautiful Eyes: Other than his lightning-shaped scar, one of Harry's most notable and frequently commented on trait is his green eyes, which he inherited from Lily.
What Do You Mean, It's for Kids?/What Do You Mean, It's Not for Kids?: Seems to fall into both because of author intent. invoked Rowling did indeed conceive the books as a children's series, despite the protestations of many older fans that it's not really for kids. But she admitted that she made the books "grow" with the original fanbase, and the last three or four aren't appropriate for the books' original elementary-school-age audience. Evidenced by the fact that the ratings of the Harry Potter movies increase with each sequel.
The seventh movie has some nudity and rather scary nightmare-inducing scenes, like Bellatrix torturing Hermione. It has a PG-13 rating. It even got a "G" rating in the Province of Quebec! (Though this can be explained by the fact Canada usually is more lenient with movie ratings, often lowering them frond what is found in other countries.)
The first novel in particular is very innocent and child friendly in its presentation of the Wizarding World. Most people tend to overlook that Harry is in mortal peril on numerous occasion throughout the tale and there are active attempts on his life, and even begins with the brutal murder of Harry's parents by Voldemort. This is popularly read as a bedtime story.
Rowling herself liked to point out to people who complained that later books became too dark that book one had a man with a face on the back of his head.
What Happened to the Mouse?: The Hogwarts Song. Remember that one? Word of God has stated that Dumbledore only asked people to sing when he was in an exceptionally good mood. We miss the second book's feast, and by the time of the third book, Voldemort has attacked twice and there's a mass murderer running around. And given their reaction the first time around, it seems highly unusual that any of the other teachers would start singing.
What the Hell, Hero?: Plenty of Dumbledore's decisions have a helping of this, chronologically starting with his refusal to confront Grindelwald during the pillaging of Europe and ending with the metric ton of secrets kept from Harry, often for no good reason. (Due to esoteric rules of magic, not telling Harry in advance that he would have to die and that he might get better is one of the few justified cases.) He gets called out on this by Snape, by Harry in book five, and post-mortem, by Aberforth and Rita Skeeter.
Dumbledore gets to do a bit of calling out himself with Snape when he realizes that Snape hoped to enact Comforting the Widow with Lily.
The Prime Minister in Half Blood Prince calls out Scrimgeour and Fudge that they neglected to warn the Muggles that Dark Wizards, Dementors and Giants trapsing around the British countryside committing random acts of terrorism and murder. This is despite the Ministry planting Kinsley and various Aurors in his staff to bodyguard him, which meant they could have warned him.
Why Don't You Just Shoot Him?: Harry only survives through books 4 on because the revived Voldemort demands a grandiose and wand-induced death. When Voldemort actually does this in Book 7, it doesn't stick. Voldemort actually tries this near the end of Book 5 when he shows up unexpectedly after Harry had thwarted the Death Eaters' plan. Luckily for Harry, Dumbledore intervenes just in time.
World of Snark: Almost everyone shows the inclination at some point or another.
Amongst the Gryffindors: Harry, Ron, Hermione, Ginny, Fred and George, Seamus, Dean and Romilda all go for it.
The other student snarkers include Draco, Pansy Parkinson, Zacharias Smith, Pavarti (when pushed) and Padma Patil (particularly at the Yule Ball), and on occasion even Luna. Moaning Myrtle and Diary!Riddle also have a few choice lines, proving this is not limited to living students.
The adults have no shortage either: Snape, McGonagall, Moody, Lucius, Sirius, Bellatrix, Molly, Tonks... In flashback, Lily, James and Lupin all prove themselves too, and even Fudge gets a few chances to indulge his inner snarker. The portrait of Phineas, too.
Finally, even Percy Weasley the perfect Prefect gets a few moments of snark, notably "I hope [Ron's] not in another girls' bathroom" in Chamber of Secrets and "Did I tell you I'm resigning?" in Deathly Hallows. No wonder so many interactions between our heroes end up degenerating into Snark-to-Snark Combat...
Your Vampires Suck: A mild case of this. The one vampire encountered in the books seemed none too frightening, though Goblet of Fire alludes to the Ministry seeing them as a sufficiently serious problem to be worth employing vampire hunters. J.K. Rowling does poke fun of a vampire who hypnotizes its victims with a boringDoorstopperof a book. It's also mentioned in Philosopher's Stone that Quirrell was supposed to have cracked after meeting real vampires (and a hag) when he decided to get hands-on experience with dark creatures instead of merely reading about them; since his stuttering, scared-of-his-own-shadow persona was an all act and what actually happened was him encountering and being corrupted by Voldemort, this story isn't conclusive, but it does suggest at least some wizards believe vampires to be truly dangerous, or else no one would have accepted this as an explanation for Quirrell's behavior.