Played with. Neville becomes a freedom fighter and a damn good one. He even destroys Voldemort's final Horcrux. However, fans who were expecting to see a showdown between him and Bellatrix due to the buildup from book four onward were left disappointed, as Molly Weasley ends up being the one to fight her. See Berserk Button below.
J.K. Rowling later ended up explaining why several characters die offscreen, point out that battles are battles and people do not die whenever the story finds it convenient. Presumably, Bellatrix gets offed by Molly because that was how that part of the battle ended up (Neville kicking ass and taking names elsewhere). These things just happen in combat.
A What Could Have Been. Florean Fortescue's disappearance/kidnapping in Half-Blood Prince. Rowling has said that this was to involve a subplot of Fortescue and the Elder Wand. Rowling cut it after realizing it went nowhere. She made this revelation in response to a question about Fortescue's disappearance in which she said he was indeed unfortunately dead and explained the dropped subplot.
Many fans agree that the final confrontation between Harry and Lord Voldemort was a bit of a let-down. Voldemort casts the Killing Curse at Harry with the Elder Wand, but since Harry is its true master, the curse backfires and kills Voldemort. From a storytelling point of view, the true climax of the novel was when Voldemort "killed" Harry in the forest (and sealed his own fate), everything after that was denouement, but Voldemort did not know that.
Averted in the film, however, where Harry and Voldemort have an epic duel for five minutes, with Voldemort flying around all over Hogwarts and Harry holding on for dear life. Then their wands induce Priori Incantatem from each other, and they duel for almost a minute before Neville cuts Nagini in two, which causes Voldemort to disintegrate due to all the Horcruxes being destroyed and his strength weakening to the point where his killing curse slowly rebounds on him.
Anti-Villain: The Malfoys. At this point, the only thing they want is for the family to survive together. In fact, the moment they learned that Draco is still alive, they take the opportunity to lie to Voldemort about Harry's fate.
Anyone Can Die: If you were really attached to certain characters, you're gonna need some tissues for this one.
In the book, Lavender is attacked by Fenrir in the Battle of Hogwarts, but is saved in the nick of time by Hermione. In the film, Hermione sees Fenrir over Lavender and he runs off, but then we see it's too late; Lavender ls lying dead on the floor, eyes unfocused and dull. Word Of God and a later published book to go with the series confirm her death.
Pius Thicknesse got cursed in the face and fell off a battlement in the book, but survived the battle and was forgiven because of the Imperius Curse he was under (courtesy of Yaxley). In the film, Pius was killed by Voldemort in a bout of rage when Ravenclaw's diadem was destroyed.
Regulus Black was also The Atoner, although he is dead before the book begins.
The Malfoy family, and Draco in particular, play with this trope. Draco legitimately regrets joining up with the Death Eaters and his role in Dumbledore's death, but he never actively tries to redeem himself, partly because he's in too deep and partly just because of a lack of character. In the end he settles for what might be called passive resistance.
For instance, his plan to save Harry from the killing curse involved: Voldemort's horcrux absorbing some of the impact, Harry's blood being used in Voldemort's resurrection, having Voldemort himself cast the curse, making sure the elder wand was not fully under Voldemort's control and finally by having Harry willingly sacrifice himself rather than continue to fight.
The part about the wand being under Draco Malfoy's control was specifically not in Dumbledore's plan, but in the end actually works to Harry's benefit. In Dumbledore's plan Snape would have killed him without Malfoy getting involved at all. This would have prevented Voldemort (or anyone else) from obtaining the Elder Wand's full power as it would not been won in a duel. Though things do end up working out even better than he could have imagined.
In the film, Ron gets very angry when Hermione is attacked by Goyle.
In case you didn't notice in any of the previous 6 books, Harry growing up with no parents is a bit of a sore point with him. Lupin and Ron both set him off for nearly abandoning his unborn son and saying that Harry doesn't have to worry about his parents in danger, respectively.
In a backstory, it is revealed that Percival, Albus Dumbledore's father, found out that his daughter hated being able to perform magic and attacked the muggle boys who attacked her.
Voldemort had a couple of them, most notably when he found out the the trio stole the Hufflepuff Cup from Gringotts. He killed the goblin who brought him the message and anyone else who was around and couldn't get away fast enough.
Big Damn Heroes: Frequently. Almost every good character gets such a moment.
The Big Damn Kiss: Ron and Hermione, the one their shippers were about to have heart attacks in anticipation of.
Bittersweet Ending: Voldemort is gone once and for all, everyone who fought in the battle is hailed as a hero. Percy, Dudley, Kreacher, and (perhaps) even Malfoy finally make peace with Harry, and for once, a competent Minister of Magic is instated. The bad news? Lots of people are dead. Lots. And, annoyingly, a few people who probably deserve death or imprisonment seem to evade it in the end (or, at least, don't have their fates mentioned in the book). It's not a perfect world.
Blatant Lies: After the ministry is taken over by Voldemort, they quickly adopt a strictly anti-Muggle policy, even setting up Inquisition-style hearings for Muggle-borns. And during one such trial, Dolores Umbridge flat out states that a Muggle-born she is interrogating is not a witch. Harry can't take any more after this. Fortunately, Word Of God states that Umbridge ended up in Azkaban for the rest of her life.
Book Ends: After Harry defeats Voldemort for the first time (when he is but a one-year-old baby) Hagrid brings him to Privet Drive using Sirius' flying motorcycle. Sixteen years later, when the Order gets Harry away from Privet Drive before the blood wards fall, Hagrid is the one that takes Harry away... on Sirius' flying motorcycle.
Bowdlerise: A very unfortunate one for the Spanish translation. The incredibly awesome as hell Molly Weasley's Precision F-Strike got treated this way, from "NOT MY DAUGHTER, YOU BITCH!" to "Not my daughter, you bad witch!". note Rises from the use of "witch" as an insult, which makes no sense in a world where every female magic-user is called a witch. Fortunately, the film upgrades it to "harpy".
Broken Pedestal: Played with with Dumbledore, when Harry realizes that not only did he make a huge number of mistakes in his past and that he was not the perfect wizard he idolized, but that he was sacrificing Harry to kill Voldemort without even discussing it with him. And inverted with Snape, who he originally thought of as this horrible person he hated, but after realising the lengths he went to in order to protect him — to the point of infiltrating Voldemort's inner circle and dying for him — thinks radically differently.
Doubles as Book Ends. In Philosopher's Stone, Hagrid takes Harry to #4 Privet Drive for the first time... in Sirius Black's flying motorbike. Guess how Harry leaves forever at the beginning of this book.
In the last film, there's a callback to Prisoner of Azkaban, where Sirius tells Harry "The ones that love us never really leave us. And you can always find them in here." *points at Harry's heart*
Harry: He won't be able to see you? Sirius: No. We're here, you see. (points at Harry's heart)
There are many references throughout Deathly Hallows calling back scenes from many of the other books. Some examples are Harry reminiscing with Hagrid about how Hagrid told him he was a wizard way back in Philosopher's Stone. Another is Ron and Hermione actually re-entering the Chamber of Secrets in search of Basilisk fangs to destroy the Hufflepuff cup horcrux.
When Moody was explaining the escape plan from #4 Privet Drive, he refers to Fred, who proclaims to be George like he did way back in the first book to his mother. Unlike Molly, Moody has no love for it.
Moody: Arthur and Fred – Twin: I’m George. Can’t you even tell us apart when we’re Harry? Moody Sorry, George – Fred: I’m only yanking your wand, I’m Fred really – Moody:(Angrily) Enough messing around!
James' first words to Snape are almost identical to a line from Malfoy's first conversation with Harry.
Malfoy (in book 1): "Imagine being in Hufflepuff, I think I'd leave, wouldn't you?"
James (in book 7): "Who wants to be in Slytherin? I think I'd leave, wouldn't you?"
The Cavalry: Brought by Slughorn, of all people. And another with Kreacher.
Conveniently Interrupted Document: Near the beginning, Harry finds a letter from one of his parents which mentions Dumbledore, and hints at a surprising revelation about his past. However, the second page of the letter is missing. He finds out much later that the revelation would have been of some use to him at the time, and that it was removed for reasons completely unrelated to any desire to keep it from him.
Cool Old Guy: With Dumbledore gone, we get his brother, Aberforth, who is almost as cool.
Neville's grandmother. Also overlaps with Badass Grandma, as when Death Eaters came to her house to try and capture her, she not only fought them off, putting one of them in the hospital, but went on the run as well. Now we know where Neville gets his guts from.
Professor McGonagall also counts, especially considering the final battle.
Corporal Punishment: We can only imagine what the hell is going on at Hogwarts while the heroes are running around the countryside. Neville certainly looks like he had a pretty rough time of it when he shows up after a year's worth of it. Apparently things would have been even worse if the Carrows had had the complete run of things. Even happens in lessons: "They had us practicing the Cruciatus Curse on first years.... That's where I got this [scar]. I refused to do it."
Cosmic Deadline: After many pages detailing a camping trip and other hairsbreadth escapes, suddenly the trio arrives at Hogwarts and truckloads of important, nay, essential information is revealed, and the plot relevant (or irrelevant) deaths start cropping up all over the place.
The cover to the American edition made it seem like Harry and Voldemort were in an outdoor coliseum during their final confrontation when it turns out to be the Great Hall at Hogwarts. Might be less of a lie than typical, though: It is a perfectly accurate rendition of the moment just after Voldemort is killed, including Harry reaching up to catch the Elder Wand. Harry and Voldemort even dueled at sunrise, and the Great Hall ceiling does reflect the sky outside, making it possibly an interpretation of the Great Hall and its ceiling.
The Danish cover is much worse. At what point does this image◊ happen in the book? Granted, it's possible that that is a representation of the centaurs and/or Hogwarts statues joining for the battle, but the actual "order allies to battle" by Harry never occurs.
Crippling Overspecialisation: Voldemort, though the revelation builds on hints from previous books. Essentially all he ever cared about was the Killing Curse (or, more generally, the Unforgivable Curses) and using Horcruxes to live forever, and from his narrow knowledge wasn't even aware that he had possessed the Resurrection Stone (he was never interested in the Hallows, however). To the point that he still uses Avada Kedavra on Harry at the end despite it having backfired (in different ways) three times before. However, this is only with Harry, with everyone else, he brings out his most powerful curses, and even when Harry's sacrifice protects everyone, Voldemort still blasts Kingsley, McGonagall, and Slughorn out of the way when duelling all three at the same time. With the final Avada Kedavra that essentially kills Voldemort, he was kind of left with no other choice. He could not curse any of the defenders because they were protected by Harry's love, and even if he killed Harry, he would be attacked by everyone else. He really didn't have a choice.
The Dark Side Will Make You Forget: Severus Snape. When he started out he was a troubled neglected boy who just wanted Lily to like him. Then he got into Slytherin and things slowly turned rather dark at the influence of his friends. Then he got into the Death Eaters and completely forgot that blood-lines didn't used to matter to him, and things got worse to the point where he was trying to bargain with Voldemort to exchange Lily's own son's and husband's lives in order to save hers. Then he came back under Dumbledore's influence and ended up putting his life on the line to save other people, including Harry. So he wavered across the "Evil" line for a fair while there, obviously.
Day Of The Jackboot: Voldemort and the Death Eaters complete their Nazi-style takeover of the Ministry of Magic.
Determined Defeatist: Aberforth Dumbledore is convinced that Voldemort is going to win and advises the heroes to give up and flee the country. Naturally, he still shows up to fight when push comes to shove.
Did You Just Scam Cthulhu?: Narcissa Malfoy is apparently a Occlumens to match the world's greatest Legilimens-perhaps even learning to do this on the fly.It is possible that Narcissa blocked Voldemort out with her love for Draco, akin to what Harry did in the fifth book.
Disney Death: Harry Potter himself, although the reader knows he isn't really dead. However, those who believed J.K. Rowling's hints that he'd die at the end of the seventh book would certainly be surprised.
Freudian Slip: Snape calling Lily a "Mudblood" turned out to be this. He claimed that he never meant to say it, but she doesn't believe him and ends her friendship with him, realizing what kind of person he had become.
Full Name Ultimatum: "You-complete-arse-Ronald-Weasley!" and "Don't you tell me what to do, Harry Potter!"
Generation Xerox: In the epilogue, Ginny's daughter Lily cries at the train station the same way she did at that age. Harry's oldest son James is a bit mischievous like his namesake. Harry's second son Albus is said to be the spitting image of him, including the eyes, and has similar fears of being placed in Slytherin. Meanwhile, Draco's son Scorpius is his own image.
Ginny's "farewell present" to Harry, cut short by Ron's interruption.
Harry's daydreams/memories when the Weasleys' Auntie Muriel remarks that Ginny's dress is "far too low-cut". Ginny follows this with a wink at Harry and Harry's thoughts drift "far away, back to stolen hours spent in secluded spaces of the Hogwarts grounds..."
Another moment came when Ron was being told to pick up his room for his brother's wedding, and he irritably responds "Are they getting married in my room? No! So why in the name of Merlin's saggy left—", before he gets cut off by his father.
And the subtext in this dialogue, it goes past very quickly so it's easily missed over all the action. Harry asks Ginny where Hermione and Ron are just before the battle. Ginny replies that they left mentioning something about finding a bathroom, prompting a Flat "What." and "You're sure?" from Harry. They were going to the Chamber of Secrets, but at this point no-one knows what they have in mind, do they?
Go Look at the Distraction: After Harry defeats Voldemort, he wants time to talk to Ron and Hermione in private, and Luna points out one of her made-up creatures, making people look away from Harry so he can escape.
Good Is Not Nice: Harry had used the occasional Unforgivable Curse in moments of extreme stress in previous books, but it really gets turned Up to Eleven in this one. Many fans complained about this and about Dumbledore's interest in the dark arts; J.K. Rowling stated that she never depicted Harry or Dumbledore as white knights.
The Guards Must Be Crazy: The snatchers fail to confiscate Ron's Deluminator and Harry's piece of mirror, despite the fact that one is a magical device and the other a potential weapon. Perhaps justified in that the wizarding world tends to focus on spells and wands, rather than the vast number of different weapons that Muggles use.
Snape, back when he first joined the Death Eaters and found out about Trelawney's prophecy concerning Harry.
Hellfire: Fiendfyre. Of course, isn't explicitly demonic, "just" powerfully magical, near-sentient and capable of burning through a cathedral-sized storehouse in minutes. Oh, and it's a lot harder to stop than start.
By Harry at the end when he has to face Voldemort so he could kill him.
Snape, really deserves a mention in that he gave his entire life to Dumbledore in return for helping to keep Lily safe, and then later to protect Harry, even infiltrating Voldemort's inner circle to do so, which eventually resulted in his death.
Voldemort is killed by his own reflected killing curse. Again.
Remember how Voldemort got so evil that he created an accidental Horcrux in Harry's scar? Hell, remember the Schrodinger's Prophecy he could've chosen to ignore, but didn't, and in doing so, created his own worst enemy? You-Know-Who is practically the king of this trope.
Crabbe (Goyle in the movie) with his own Fiendfyre spell.
Jack Bauer Interrogation Technique: Harry, Hermione, Ron, and Kreacher, after capturing Mundungus, pretty much use this trope to force him to reveal who he sold Slytherin's Locket to, and then (although by accident rather than deliberately, due to the shock of the revelation of who he sold it to) scald him.
Voldemort. Try to act surprised. The movie one-upped it though, where he was not only killed by the Avada Kedavra backfiring on him from the Elder Wand, but he also ended up disintegrated as well, not even leaving his body behind.
Crabbe with his own Fiendfyre. In the movies, it's Goyle, with his other half simply written out.
Bellatrix Lestrange at the hands of Molly Weasley after the former attempted to murder Ginny. The movie one-upped by having Molly hit her with another spell, causing her to shatter and exonerating Molly from actually killing her.
Leaning on the Fourth Wall: Rowling has stated that the phrase on the Snitch ("I open at the close") is one in regards to the books themselves. Specifically, Deathly Hallows takes place in the 1997-1998 academic year. In Britain, 1997 was the year that Harry Potter and the Philosopher's Stone was published. In America, Harry Potter and the Sorcerer's Stone wasn't released until 1998. The book series opens inthe real world during the years that the book series closes in the Wizarding World.
Love Redeems / Love Hurts: Snape gets hit with both with regards to Lily. He not only fails to save her, but then spends the remainder of his life trying to protect the son she had with the man he hated, despite the fact that he tried to keep him in detention for most of his school life. It probably didn't make things any easier that Harry looked exactly like James but with Lily's eyes. Ouch.
Okay, so everything is basically magic, but the true story of the Deathly Hallows is never fully explained. Are they powerful magical items made by skilled wizards, or did they really meet death and he gave them the items? There are elements of them which can't be explained within the continuity of the story, unless you accept the story about Death.
Also, everything that happens in "King's Cross". As Harry says, "Is this all in my head or is it real?" and gets a Mathematician's Answer in response. Since Harry doesn't learn anything he couldn't have worked out on his own, there's really no way to be sure.
Moment Killer: Twice: once by Ron and the other time by Harry. Harry did have a good reason for it, though.
Harry: OI! There's a war going on here!
Monster Fun Facts: Many books have a passage like this when Harry is learning about monsters in school; in this one Harry doesn't go to school but runs down a list of things at Voldemort's command to the Dursleys (who don't know much about magical stuff), including:
Harry: ...and Inferi — that is, dead bodies animated by a dark wizard...
Morality Pet: Lily for Severus. The fact that she was dead for seventeen years didn't seem to change this fact.
Mortality Ensues: The Horcrux-destruction plot is all about causing this for Voldemort.
MST3K Mantra: In-universe, when reading the Tale of the Three Brothers, Harry questions the sudden appearance of Death. Hermione reminds him that it is a fairy tale.
M-Word Privileges: Hermione refers to herself as a Mudblood and when Ron objects, she explains that she's proud that she can refer to herself that way instead of the Death Eaters doing it.
My New Gift Is Lame: Pointed out by Ron when Hermione gets a book of fairy tales, Ron gets an item which can manipulate light, and Harry gets... an old snitch. Harry, however, knows that with it coming from Dumbledore there must be a secret involved, though — and there is. Also the Snitch was the very one that Harry caught in his first ever Quidditch match, which if anything gave it some sentimental value, which in fact was useful to conceal even more of its true purpose from the Ministry.
Naked People Are Funny: Mad-Eye's plan to sneak Harry out of his house involves everyone transforming to look like him and flying off in all directions. When they change clothes, Harry is annoyed that no-one is particularly bashful about getting naked while disguised as him.
Negate Your Own Sacrifice: Harry has to die, since he's a Soul Jar for Voldemort. Fortunately Voldemort's new body was made with Harry's blood, which anchors him to the living world. Harry didn't actually know this would happen and fully expected it to be a Heroic Sacrifice. Though the blood wasn't enough in itself; according to Dumbledore, Harry's decision to let Voldemort kill him rather than keep fighting was what "made all the difference".
Never Mess with Granny: Aurors in their prime try to take down Augusta Longbottom. One of them is still in the hospital at the time of the final battle.
No Man Should Have This Power: Harry regards the Hallows as this. At least the Wand and Stone (from dialogue in the book, one can assume he kept the Cloak). He lost the stone in the forest, and deliberately refuses to look for it again. Also, in regards to the wand, in the book, he put it back in Dumbledore's grave with the hope that he, Harry, would die naturally so the cycle of violence over the wand would end. In the movie, he is much more pragmatic and simply snaps the wand in two.
Ron and Hermione recovering the basilisk fangs from the Chamber of Secrets. This could have been used to show another spiritual illusion to try and stop them, like with the locket, but it was left out due to the book's Cosmic Deadline (see above). Happily, it's included in the movie.
In the book, before the Dursleys leave Privet Drive, Dudley shows concern about Harry’s safety, tells Harry that he doesn’t consider him to be "a waste of space," is thankful to him for saving his life, and even shakes his hand. For Dudley, this is positive Character Development and a Crowning Moment of Awesome rolled into one, because it presents Dudley as finally accepting and appreciating Harry. Disappointingly, this is left out in the film, though it's included in the Blu Ray deleted scenes.
Also in the book, Dean Thomas is seen in the final battle casting spells with a new wand, having obtained it during the battle, as we see him enter the final battle without one. It's true he's a minor character, but this is an unarmed teenager who took ownership of a wand by forcefully taking it from a trained killer in the middle of a kill or be killed melee between good and evil.
Prodigal Hero: Harry had to flee an hide all over England to stay a step ahead of Voldemort, but when the last Horcrux was hidden in Hogwarts and he found that out, he rushed to Hogwarts to find it, which sparked the Final Battle.
Protagonist-Centered Morality: Subverted. Harry uses the Cruciatus curse, but this was so that the audience would recognize his flaws, not change their mind about the appropriateness of Dark Magic. Also uses the Imperius Curse on both a goblin and a nosy Death-Eater during their raid on Gringotts in search of a horcrux.
The Ministry of Magic under Voldemort. The Death Eaters' skull is even similar to the totenkopf of the SS.
Nurmengard, Grindelwald's prison for his enemies, is a thinly-veiled Auschwitz, right down to the slogan written over the gates. Considering Grindelwald himself was later imprisoned there, it might double as a reference to Nuremberg.
R.A.B: when he discovered what a monster Voldemort was, stole the Horcrux and died in the process.
Also Severus Snape.
Redemption Rejection: In the film, Draco is called by his parents to join the Death Eaters, and he gets several long seconds of worry before siding with them. "Them" being his parents, not the Death Eaters. During the final battle, he and his parents flee Hogwarts instead of staying and fighting for Voldemort.
Red Herring: Neville. Many readers thought this book would have Trelawney's prophecy turn out to be that he was the one who would bring down Voldemort. He has a bigger part in it than most, though.
Refusing Paradise: Dumbledore offers Harry the chance to pass on to the next world, but Harry chooses to continue the fight against Voldemort.
Retired Badass: Averted with Harry and Ron when they grow up, but played straight with almost every other major character. Particularly Neville, who settled into a nice, quiet teaching position at Hogwarts. Word Of God says Ron helps run Weasley Wizards Wheezes with George and also after the battle of Hogwarts that he does become an Auror with Harry and Neville. Whether he's still an Auror or working with George at the time of the epilogue is unknown.
Revealing Skill: While being ambushed en route to The Burrow in the beginning, Harry unwittingly reveals himself when he uses the Disarming Charm — his signature move — against Stan Shunpike (who is being forced to participate in the ambush against Harry via the Imperius Curse.)
Room Full of Crazy: One might count Luna's bedroom. Granted, the girl hasn't a malicious bone in her body and none of it is sinister, but, well... portraits of people you like all linked by gold chains made of the word "friends" does go a little beyond Cloudcuckoolander. Opinions differ on whether this is heartwarming or stalkerish. All of the Lovegoods' house counts, really.
Sadist Teacher: The Carrows, a pair of ruthless Death Eater siblings, take over disciplinary matters and Defense Against the Dark Arts at Hogwarts this year. You know they're bad when Neville says they make even Umbridge look good by comparison.
Secret Test of Character: The Sword of Gryffindor was placed under the frozen lake ostensibly to serve as some kind of test of bravery and determination. Harry realizes that immediately, but still points out that it seemed less of a test of character and more making things unpleasant for the hell of it.
Narrator: Where "chivalry" entered into this, he thought ruefully, he was not entirely sure, unless it counted as chivalrous that he was not calling for Hermione to do it in his stead.
Self Induced Allergic Reaction: Hermione's quick thinking allows her to prevent Harry from being recognized by the Snatchers when they're surrounded in the woods. However, the disguise isn't foolproof, and the trio have to rely on Malfoy to look the other way and pretend he can't tell whether it's Harry or not.
Sleep Cute: In the book and the film Ron and Hermione are asleep next to each other, with their hands lying so they appear to be reaching out for each other. Given a horrifying echo in Part II when Together in Death Remus and Tonks' bodies are laid out in the exact same way.
Spotting The Thread: Luna Lovegood sees through Harry's disguise at Bill and Fleur's wedding simply from the expression on Harry's face.
Start of Darkness: A variation. This time, instead of seeing Voldemort's transition from cute, troubled kid to full-on genocidal maniac, we get to see Snape's transition from cute, troubled kid to troubled heartbroken adult, and Dumbledore's transition from cute, troubled kid to wise manipulative Chessmaster — both of them dabbling considerably in the Dark Arts for a while. Apparently coming from a broken home is a pre-requisite for this kind of thing. Interestingly, all three of them were Insufferable Geniuses as teenagers.
Sue Donym: The Potterwatch radio crew refer to themselves by ridiculously transparent pseudonyms based on their actual names: Lee Jordan is River, Kingsley Shacklebolt is Royal, Fred Weasley (weasel) starts as Rodent (quickly changed to Rapier, presumably for "rapier wit"), and Remus Lupin exhausts the last untapped blatant reference in his name by going as Romulus. To their credit, Kingsley is the wizard James Earl Jones as far as vocal recognition goes and they would have been killed on sight anyhow for belonging to the Order of the Phoenix, so protecting their identities wasn’t worth much.
Professor McGonagall leads the defense in the Battle for Hogwarts to give the Power Trio the time to find the final Horcrux, even though she has to trust Harry by his word alone.
Also, former Butt Monkey Neville Longbottom lead the student resistance in Harry's absence.
Reading between the lines, Kingsley Shacklebolt becomes the Big Good after Dumbledore's and Moody's deaths and later becomes the first competent minister of magic in years. But from Harry's point of view he remains a peripheral character.
Sword of Plot Advancement: The Horcrux-destroying plot only takes off after Harry, Ron and Hermione find where Gryffindor's sword was hidden.
Take Off Your Clothes: Hermione makes Harry and Ron take off their wizards' robes so they can pass as Muggles.
That Liar Lies: Harry shouts "LIES!" to no-one in particular when first reading some of the media references to Dumbledore's Feet of Clay. The melodrama of this is lampshaded in that a Muggle neighbor is shown to overhear and glance around nervously.
Took a Level in Badass: Virtually everyone, but particular standouts include Mrs. Weasley, Prof. Slughorn, and above all Neville Longbottom, who in some ways really is the biggest hero in the story. Special notice for Sybill Trelawney, who took out several Death Eaters (including Fenrir Greyback) by using magic to throw crystal balls at them.
Too Dumb to Live: Sure, Voldermort. Continue to cast the Killing Curse on "The Boy Who Lived", even though it is clear that the spell backfired on you. Brilliant.
Tracking Device: A running quirk in the first book, revealed by Ron in the last: there's a reason why wizards won't dare speak Lord's Voldemort's name. The spell that made that possible wasn't in use until the last book. So it was safe to actually say Voldemort's name until that spell was cast.
The heroes had one in place as well. Dumbledore originally planned to depower the Elder Wand by having Snape kill him by consent. This was ruined when Draco Malfoy Disarmed him during their encounter, and Dumbledore never got a chance to reclaim it. Later, Harry Disarmed Draco of his usual hawthorn wand, taking it for his own—and by doing this, Harry (by pure luck) became the master of the Elder Wand, essentially preventing Voldemort from ever becoming its master. This is eventually what allows Harry to win against Voldemort.
Villainous BSOD: Averted. The master of a Horcrux can repair his soul by feeling regret — which, given what their creation entails, often means that they'll feel so much pain that they'll die — but Voldemort has to be killed the normal way. Having to do it the old-fashioned way is meant to illustrate that Voldy is irredeemable.
What Could Have Been: Working titles were Harry Potter and the Elder Wand and Harry Potter and the Peverell Quest. The latter was rejected for being way too cheesy, but the former would have made a lot more sense.
Snape delivers one of these speeches to Dumbledore, after he reveals that Harry (whom Snape has been protecting) must die in order to defeat Voldemort. It's the one time that Snape gets properly angry at Dumbledore.
Harry delivers one to Lupin, when he offers to abandon his family to help the trio on their quest, largely out of self-loathing.