The one thing that all and every teacher agree on: Umbridge must go.
When someone is such a horrible teacher that Severus Snape is rising up against her, you know it's awesome.
One of Neville's better crowning moments of awesome is in when he's crippled, unable to cast spells, and still sticks a Death Eater in the eye with Hermione's wand.
The fact that Harry and his friends, a bunch of fifth-years and fourth-years, managed to escape and defend themselves against about a dozen trained and deadly Death Eaters for quite some time was pretty amazing. As is the fact that Harry initially buys time by taunting them about Voldemort being half-blood.
Fred and George Weasley get their moment when they leave the school.
"Give her hell from us, Peeves."
It gets even better: not only does Peeves do as he was told, he saluted Fred and George as they left. Earning that amount of respect from Peeves, of all people...
As well as everything that the mass of unnamed students who took up after the twins left did. Hexing Umbridge's minions, making themselves sick to get out of class, putting Nifflers in her room, the list goes on.
And before that, the speech they give to Hermione declaring that they don't care about getting thrown out anymore; in fact, they're only staying at all to do their bit for Dumbledore.
One of the Slytherins tries to use his Umbridge-given powers to bully Fred and George. He ends up stuck in Vanishing Cabinet limbo for weeks.
Which is mildly degraded by the fact that this (very inadvertently) led to Dumbledore's death.
But he would've died anyway due to wearing the Gaunt's ring later that summer. So this actually gave Dumbledore a quick and painless way out.
Bellatrix overdid her share of amazing things during the series, but her crowning moment of awesome occurred in the end of The Order of the Phoenix, where she defeated Tonks, Sirius, and Kingsley, which were half of The Order of the Phoenix present at the battle. Not only that, but she deflected Dumbledore's spell, while all the other Death Eaters were easily caught by that same spell. None of this was shown during the movie, but Helena Bonham Carter's acting made up for that flaw. Of course, she was later owned by Dumbledore's enchanted statue, but still.
Dumbledore destroying the Ministry's trumped-up charges against Harry and calling them out for their corruption, all while being completely calm and extremely polite.
Damn near everything McGonagall does, period. Especially her response to being inspected by Umbridge in Order of the Phoenix.
This deserves some elaboration: Umbridge is constantly interrupting McGonagall's lesson to harp on some trivial thing. Eventually, McGonagall turns to her and calmly, but with unmistakable snark, asks how she expects to learn anything about McGonnagall's teaching methods if she insists on interrupting, as talking during the Transfiguration lesson is not generally allowed. Not only does Umbridge hold her tongue until the end of class after being admonished by McGonagall, she doesn't follow her around as she does with the other teachers. Harry wonders if this is because she thinks it wouldn't be allowed.
On a similar note, her inability to join Peeves in chasing Umbridge from the school because he had stolen her walking stick, which he used to watch her with. The way it's written - and said, on the audio tape - makes it plainly clear that Peeves went to her and told her explicitly what he was going to use it for and she allowed him to use it.
McGonagall railing all over Umbridge's attempts to crush Harry, saying she'll do everything she can to get him made an Auror even if she has to die in the process, all the while giving Umbridge the hate glare. Awesome.
Made even more awesome by the fact that Harry doesn't just become an Auror, but the head of the Aurors. Yes, McGonagall did it in the end!
"You are raving," said McGonagall, superbly disdainful. "Superbly disdainful". I mean, right?
Professor Umbridge stood up. Since she was so short, this didn't make much of a difference... Professor McGonagall stood up. In her case, the effect was much more impressive.
McGonagall's answer to Umbridge about Harry getting poor grades in her subject: "I should have made myself plainer: he has achieved high scores on exams applied by a competent teacher." which, at that point, pretty much meant the fake Moody from the previous year... and Lupin. Umbridge must have loved that.
It may not have achieved anything, but she ran into battle against four Aurors to stop them arresting Hagrid. And taking four Stunners in the chest in the process. Madam Pomfrey assures Harry that none of those four Aurors, whom McGonagall herself earlier described as exceptionally talented elites who underwent three years of harsh training, would have stood a chance against McGonagall in a fair fight. They had to resort to suddenly whirling round to attack her without warning.
McGonagall protecting Trelawney from Umbridge. She may disdain the woman's profession, but NO-ONE is throwing one of her teachers out but her. Her moment goes to Dumbledore in the movie, but Maggie Smith's ice-glare to Umbridge while standing in front of a sobbing Trelawney deserves a mention of its own.
Umbridge: Something you'd like to say, dear? McGonagall: There are several things I would like to say!
Also, Snape's response to Umbridge.
Umbridge: You applied for the Defense Against the Dark Arts post? Snape: Yes. Umbridge: And you were unsuccessful? Snape:(in a "what the hell do you think" voice) Obviously.
Perfect delivery by Alan Rickman.
Dumbledore vs. Voldemort, which is somehow made more awesome in the film. And while we're at it, Dumbledore's Big Damn Heroes moment.
Harry and Neville are cornered and facing half a dozen Death Eaters. The Order of the Phoenix arrive, and things even out, until another few Death Eaters arrive. Things are now looking very bad for the heroes, and then Dumbledore arrives. Before the end of the page, all but two Death Eaters are disarmed and bound in the middle of the room — and about half of that is Harry thinking, "awesome, Dumbledore's here! We're saved!"
This is pretty justified, as it's been well-established across the series that you do not make Molly Weasley angry. Fred and George would know how she would react to their antics and how she would disapprove. They'd sooner just get detention, than have her on their case.
After Umbridge grabs one of the students in Dumbledore's office, shaking her very hard, before anyone can see him, Dumbledore pulls out his wand and says that he will not allow her to harm one of his students; it even mentions that it was one of the few times that anyone has ever seen Dumbledore angry. May also double as a Crowning Moment of Heartwarming to see how much Dumbledore cares for his students. During that scene, Kingsley modified that student's memory to make it seem like there were only two meetings of the DA. On the spot, without getting noticed.
Dumbledore assures Fudge that he won't be taking on him, 2 Aurors and both his Senior and Junior Undersecretaries alone.... "unless [they were] foolish enough to force [him]".
"You have to admit, Minister, Dumbledore's got style."
"You seem to be laboring under the delusion that I am going to — what is the phrase? 'Come quietly.' I am afraid I am not going to come quietly at all, Cornelius. I have absolutely no intention of being sent to Azkaban. I could break out, of course — but what a waste of time, and frankly, I can think of a whole host of things I would rather be doing."
This has to be elaborated on: Azkaban is a prison guarded by creatures that literally suck all the joy and happiness out of the prisoners, leaving most of them with no will to even contemplate breaking out...and Dumbledore says he wouldn't want to break out because it's a waste of his time and he'd rather be doing something else. He's talking breaking out of a maximum security wizard prison the way most people talk about minor troublesome tasks. He's that powerful.
Hermione showing just how much she owned Rita in the Three Broomsticks. Also (while pretty cruel) that she had the foresight to see that one of DA might betray them and came up with a jinx that even Pomfrey couldn't remove to mark them — and her spell incapacitated Marietta enough that she was prevented from spilling too much about the DA. Not to mention that she came up with a pretty good lie to keep Umbridge from torturing Harry.
Snape, showing nothing but contempt to Umbridge when she catches Harry and the DA. Especially awesome when he's telling her to suck it using lame excuses when asked for Veritaserum, and you realize later on that he was the first to inform the Order of the situation.
And he gets in a lovely little Stealth Insult: "You surely didn't use it all? I told you that three drops would suffice."
Hermione Granger vs. the Ministry of Magic's propaganda campaign. Hermione wins.
"None of them had seen Hagrid in a real temper before..." Professor Umbridge has two teachers dismissed from Hogwarts during her reign as High Inquisitor: Professor Trelawney (Divination teacher) and Professor Hagrid (Care of Magical Creatures teacher), the former because she wasn't actually a prophet (or so she thought), the latter because he was a half-giant. When Professor Trelawney is dismissed, she cries like a baby, begging Umbridge to let her stay, saying "Hogwarts is my home!" and generally being really pathetic, even though it was a sad scene nonetheless. When Hagrid is dismissed, does he cry? No. Does he beg to be allowed to stay? No. What does he do? He delivers an epic Curb-Stomp Battle to the four Aurors (read: exceptionally powerful wizards) that came to take him away, with his bare hands, while holding his unconscious dog under his arm, while the whole time Stunning Spells are bouncing uselessly off him (which Hermione later explains is due to his giant's blood, giants being notoriously hard to Stun). Umbridge is freaking terrified, two of the Aurors get knocked out cold by Hagrid (who as mentioned before, is not using any magic, and is facing a team of the most highly-skilled wizards there are), and it ends with Hagrid fleeing into the Forbidden Forest, still being bombarded with spells that are doing absolutely nothing to him.
Dawlish: "Be reasonable, Hagrid!"
Hagrid: "Reasonable be damned! Yeh'r not takin' me like this, Dawlish!"
Even better... Before the Aurors hit McGonagall and Fang, Hagrid was just defending himself and trying to reason. Them attacking McGonagall and Fang hit his Berserk Button, and only then he delivered a brutal Curb-Stomp Battle in two seconds flat. He went in a Roaring Rampage of Revenge... Then saw they weren't worth the trouble, picked up his dog and quietly left.
Neville in the Ministry of Magic standing up to Bellatrix. Keep in mind, this isn't some rent-a-cop Death Eater. This is Bellatrix freaking Lestrange, arguably the most dangerous witch in the world, the one who tortured his parents into insanity. And not only does he meet her taunt ("Why, I've had the pleasure of meeting your parents, boy!") with pure, unadulterated rage as opposed to fear, he charged in to save Harry. Without a wand that didn't work properly for him. Unable to pronounce spells. His line "HE'S DOT ALONE! HE'S STILL GOD BE!" (Translation: "He's not alone! He's still got me!") qualifies as his first huge CMOA in the series. It was just a taste of the awesome to come.
The YMMV part of the above line is that it definitely was NOT a Crowning Moment of Awesome for Harry at that time (who actually Face Palms upon hearing it). At the time, Neville showing up was the worst possible thing that could have happened to Harry, given that for one, he couldn't use his wand properly (his nose was broken and it affected his speech, so he couldn't pronounce the incantations properly) and for two, he was, well, Neville, and they were fighting a massive group of Death Eaters.
He was, in the DA, improving so rapidly that near the end of their lessons with Harry he was the second person after Hermione to master the spell they were learning. And even though he was injured, inarticulate and unable to perform magic, he still charged an armed Death Eater who could've killed him and stuck a wand in his eye to save Harry. Gryffindor, indeed.
"Weasley Is Our King." That is all.
The title of the 36th chapter (yes, a chapter title is a CMoA) says everything you need to know about Voldemort's true view of Dumbledore: "The Only One He Ever Feared"
The whole chapter is a CMOA for Dumbledore and Voldemort. The two most powerful wizards in the world show us, definitively, how they earned their titles.
Harry subdues Bellatrix while tracing her down, tapping into his Unstoppable Rage. This is the woman known as Voldemort's Best Lieutenant. She's supposed to be Voldemort's most skilled Death Eater, except for Snape. Harry has only ever had one, maybe two, competent defense against the dark arts teachers and five years experience of fixing Hogwarts' problems on his side. Now imagine Harry with proper teaching or Auror training. He could very possibly approach Dumbledore's level in his adulthood if he is properly taught.
Peeves is at his finest chasing off Umbridge and it is definitely one of the highlights of the book, especially for standing apart from the rest of the book.
After a Quidditch match against Slytherin, Malfoy is being a poor sport and throwing his usual insults at the Weasleys and Harry. Harry is ushering the twins (Fred and George) away when Malfoy drops the bombshell: he insults Harry's deceased mother. A 3-on-1 brawl begins. Needless to say, it ended awesomely for the twins and Harry, despite the fact that Umbridge punished them.
Two-on-one: Fred was being restrained by three people and later regrets not having been able to contribute.
An off-page, downplayed one for Lupin, who is the only Order member bar Dumbledore to escape the battle in the Department of Mysteries unscathed. Bear in mind that this same battle ended with Tonks (a junior Auror) unconscious, Moody (a hugely experienced Auror) pretty much incapacitated, Kingsley (another experienced Auror) injured and Sirius dead. Not bad for a geekyteacher.
Madame Maxime gets an off-page one as described by Hagrid. The Gurg (chief giant) they'd been negotiating with was killed in an uprising two days after they'd managed to make contact and the new one turned out to not be as welcoming. Hagrid was grabbed by two of the new Gurg's men and says that would have been the end of him if Maxime hadn't been there. "She pulled out her wand an' did some o' the fastes' spellwork I've ever seen. Ruddy marvelous. Hit the two holdin' me right in the eyes with Conjunctivitus Curses an' the dropped me straightaway—" Considering whose spellwork Hagrid has seen in his time and how multiple spells later bounce off him when he's only half-giant, this is high praise indeed.
Sirius decking Lucius at the start of the fight in Order of the Phoenix. "Get your filthy hands off my godson. *BAM!*" Malfoys seem to come off on the wrong end of CMoA's.
"Sorry, Professor. But I must not tell lies." note To put it into context, Professor Umbridge is begging for her life, pleading to not be attacked by the centaurs she rather stupidly insulted to their faces. She pleads, "Potter, do something! Tell them I mean no harm!" Harry just glares at her (she did, after all, force him to carve "I must not tell lies" into his own hand for hours at a time as "punishment" for trying to get people to believe that Voldemort is back) and says the above line.
The Weasley twins destroying Umbridge's classroom... with fireworks... on brooms... during an exam.
The whole scene was kickass: And after destroying her classroom, they create a giant fiery dragon's head, which chases after Umbridge. Then after it clamps down on her, it splits off into hundreds of little rockets, smashing into every single one of herprecious decrees. They all fall off the wall, making a huge mess while the twins fly out of Hogwarts, with every single student cheering them on. The scene lingers on a giant W firework floating in the sky.
At one point in the crowd, we see Professor Flitwick. He does a victory pose.
When Dumbledore steps out of one of the fireplaces in the Ministry of Magic to fight Voldemort with one simple line. "You shouldn't have come here tonight, Tom."
Voldemort is no slouch during the final battle, producing a huge serpent made of fire and an implosion that shatters everything that's made of glass, then sending every shard of glass Dumbledore's way. For someone who fears Dumbledore, he certainly held his own.
Dumbledore's escape from an entire room of wizards, including Aurors, while basically taking them all down with one shot? That was when you first saw why Dumbledore had the rep he did.
Ginny pulling off a Reducto spell at the Department of Mysteries.
Snape's responses to Umbridge. All of them, but especially, "...No idea."
Snape's legendary snark:
Umbridge: You first applied for the Defense Against the Dark Arts post. Is that correct? Snape: Yes... Umbridge: But you were... unsuccessful? Snape:(with unbelievable sarcasm) Obviously.
Luna's CMOA from Order: during the fight in the Department of Mysteries, Luna (already bleeding from her lip) is confronted by a Death Eater flying towards her from a great height. The camera shows her from the Death Eater's POV as she looks up at him placidly, pulls out her wand and (with an expression of mild curiosity on her face) hits him with a levitation spell that's so powerful it blasts him backwards into a shelf of prophecies. Now, imagine what she could do if she was angry...
Bellatrix: Neville Longbottom, is it? How's Mum and Dad? Neville: Better, now that they're about to be avenged." (pulls out wand)
In the Department of Mysteries, Moody bangs his staff on the ground, launching a spell from it and taking down a Death Eater.