Harry Potter/Harry Potter and the Deathly Hallows/WMG

Dudley knows that Harry has a girlfriend called Ginny.
In HBP, Harry starts having dreams about Ginny because of his growing (though largely repressed) romantic feelings for her, and it has been mentioned on a couple of occasions that Harry talks in his sleep. He may have dreamed about her over the summer out of lonesomeness and longing and Dudley can apparently hear him loud and clear, since he's able to taunt Harry about Cedric's death a couple years before, which he couldn't have otherwise known about. It is reasonable to assume that Dudley knows that Ginny is a young witch in school with Harry, and is apparently the object of Harry's affection. It is not known if he knows what she looks like,her personality or that she's the younger sister of Fred and Gorge Weasley.

The eavesdropper heard the entire prophecy, and arranged to tell only a fragment.
Trelawney describes the eavesdropper's "rude interruption" as having happened after she felt a bit queasy -- an inconsequential queasiness that she still remembers some seventeen years later, mark you -- and, being totally oblivious to what had occurred, she has no reason to lie. Dumbledore, however, whose version is utterly incompatible with Trelawney's, has every reason to lie. This is also his Ironclad Reason, which explains why he won't discuss that with Harry, either. His understandable guilt regarding the incident inspires his mutterings in The Cave and his over-sheltering of Harry.

Dumbledore is actually Ron Weasley, sent back in time. (A.K.A. "Weasley Is Our King")
During the chess game in Philosopher's Stone, Ron acts as both the knight and as the king telling Harry and Hermione what moves to make. Logically, if this game is symbolic of the series as a whole, and Dumbledore is the "king" of the wizards battling Voldemort, then Ron must, therefore, be Dumbledore. If Ron was caught in an accident with a Time Turner, he could assume the role of Dumbledore and establish a Stable Time Loop based on his limited knowledge of the future.
 * He had red hair when he was younger, though.
 * And a long nose.
 * That is just that wizards are cousins and Gryffs are even closer cousins.
 * Disagree: Ron is poor, DD is rich; Ron has the emotional range of a teaspoon, DD knows how to manipulate human emotions; Ron is Harry's best friend, DD sent Harry to the Dursleys and set up a cunning plan to murder him.
 * Dumbledore actually died of old age and Ron replaced him in POA
 * Dumbledore actually died of old age and Ron replaced him in POA

Harry is just a distraction for Voldemort, it's really Neville who is going to defeat him.
The prophecy stated it could be either, but Dumbledore said Voldemort "chose" Harry. But Dumbledore has been shown to be wrong before. Prediction: Harry and Voldemort have a climactic duel, Harry loses, but then Neville strikes Voldemort down while he's gloating.
 * That would have been the best ending ever! Too bad it didn't happen.
 * It came pretty close actually. Neville really stepped up near the end. If it hadn't been that Harry was already established as The Chosen One, Neville might have had an even deeper role in the overall plot. Mugglenet even suggested the theory that had something like this happened, it would have given the series an even more poignant ending in one of their books, entitled, simply enough "Harry Potter Should have Died".
 * It came pretty close actually. Neville really stepped up near the end. If it hadn't been that Harry was already established as The Chosen One, Neville might have had an even deeper role in the overall plot. Mugglenet even suggested the theory that had something like this happened, it would have given the series an even more poignant ending in one of their books, entitled, simply enough "Harry Potter Should have Died".

Harry did die in book 7.
Rather than surviving, Harry went to heaven. In heaven, he imagined the entire defeating Voldemort. Voldemort proceeded to learn that it really was Neville, as described in the jossed theory.
 * This theory wins the Fridge Brilliance award, because of how it applies to the prophecy. Voldemort chose Neville "as his equal"...by disregarding him and going for Harry, meaning Neville was not bound to Voldemort as Harry was, leaving Neville free to act. And because Voldemort was so focused on Harry, he knew nothing about what Neville could do, thus resulting in whole "power he knows not" bit.

Snape is a good guy.
Snape's morality has been dubious over the course of the whole series, but his excuses at the beginning of Half-Blood Prince for why he "seemed to be" siding with the good guys have plausible denial written all over them. You'll also notice that when he killed Dumbledore, the latter didn't specifically say "Please don't, Severus!"; he simply said "Please, Severus!", and he was actually begging Snape to go through with killing him. Dumbledore's death was all part of an overarching plot to help defeat Voldemort.
 * No. At first glance both Harry Potter and Star Wars seem to be Good Versus Evil stories but the War is Light Versus Dark applying Blue and Orange Morality. Snape is on the Light side = DD's side but Light Is Not Good.
 * No. At first glance both Harry Potter and Star Wars seem to be Good Versus Evil stories but the War is Light Versus Dark applying Blue and Orange Morality. Snape is on the Light side = DD's side but Light Is Not Good.
 * No. At first glance both Harry Potter and Star Wars seem to be Good Versus Evil stories but the War is Light Versus Dark applying Blue and Orange Morality. Snape is on the Light side = DD's side but Light Is Not Good.

The Sorting Hat was the last Horcrux.
A theory heard before Deathly Hallows came out was that when Voldemort was in Dumbledore's office in the Pensieve flashback in Half-Blood Prince and he reaches for his wand, he was secretly casting the spell that sends a soul fragment into a host object - in this case the Hat. Then the fragment corrupted the Hat, making it send anyone with the potential for evil into Slytherin, where Voldemort had contacts and could easily recruit them, regardless of what House they were actually suited to.
 * Riddle cast a spell to burn the Hat while Neille was wearing it. I assumed that the Hat was only slightly charred, but the text ain't precise. Riddle was holding the Idiot Ball throughout bk7. He would have desroyed the Hat ifn it was a horcrux.
 * Riddle cast a spell to burn the Hat while Neille was wearing it. I assumed that the Hat was only slightly charred, but the text ain't precise. Riddle was holding the Idiot Ball throughout bk7. He would have desroyed the Hat ifn it was a horcrux.

Stubby Boardman is really Sirius Black.
Seriously!
 * Ahem. Don't you mean 'Siriusly!'?
 * He is the only character, beside the first year School song and Luna Lovegood later, that we see singing. He constantly sings God Rest Ye Marry Hippogriffs at Christmas.
 * And Stubby Boardman did retire and disappear from public view in 1980, and no one's been able to find him since...probably because the next year, Sirius got locked up. The math all works out. And we had no idea what Sirius was doing after graduation except secretly working for the Order, and he couldn't be living with James like he used to, James had gotten married and had a kid. Sirius had to have some actual real job, since his family had cut him off.
 * And Kingsley thought Sirius would find the Quibbler with that information 'interesting', so maybe Kingsley knows it's true. Arthur thought it was 'amusing', so probably doesn't know, but they were hardly in a place where Kingsley could correct his misconception. Just because Harry thinks it's crazy doesn't mean it can't be true.

"Stubby Boardman" was a Line Of Sight Name that Sirius invented when he was in a tight pinch.
One day, the Marauders were in trouble for some reason (as usual). This time, they quickly passed themselves off as a music band and came up with the name "Hob Goblins", which was also a Line Of Sight Name, probably a stand in for the Beatles. Naturally, they proved a hit, and so they carried on the deception for several years, à la Hannah Montana. It ended only when... you know, three-fourths of them were dead, in Azkaban, or living as someone's pet rat.
 * Therefore the Ministry of Magic has a 13 year Statute of Limitations. Why did she take so long to announce the alibi? Ministry sent Sirius to Azkaban without a trial and decreed that no-one may publish any defence for 13 years. When the edict expired, she wrote in.

Speaking of "Sirius Denial" style theories, Lily Potter is an Animagus and Hedwig is her alternate form.
There's no real evidence for this within the books (and it was obviously Jossed), but it did pop up every so often in Harry Potter discussion boards and is too out-there not to warrant a mention here.
 * Well, that makes  absolutely awful. And she's obviously Crookshanks, who actively sought out Harry('s friend). She was intelligent, friends with Padfoot, and tried to keep Ron away from Hermione to make Harry happy. That pesky little thing about him being a male is because Hermione didn't quite know how to tell boy cats from girl cats, and by the time she read a book on cat sexing, was too arrogant to admit she was wrong about it.
 * Jossed.
 * Wait, what? Do you mean "Jossed", Or did JKR actually Joss Lilly being specifically Crookshanks?
 * Yes, J. K. Rowling really did specifically say that Ccrookshanks is not an animagus in an interview. The theory had been popular since PoA came out.
 * Whoever suggested that Lily is Crookshanks: Are you really that oblivious to how much "Lily Lives!" theories cheapen her sacrifice? Any loving mother, when confronted by a psychopath who wants to kill their child, would offer themselves up in place of the child; to suggest that Lily wouldn't is to suggest that she was a selfish shrew.
 * This troper firmly believes the following- Lily did sacrifice herself, meant to die in place of harry, and so on and so on. But fate/Death/God/Saint Peter or whoever offers her soul/spirit a choice- she can watch from above/the afterlife, or she can spend a few years as, say, Crookshanks. When the cat dies, she will return to her dead human spirit state. kinda like Zee's grandma in The Shadow Thieves. Alternatively, the choice giver uses a good form of the horcrux spell to allow part of her soul to remain alive, in the form of Crookshanks, and the other to go to heaven/the afterlife, until the cat dies and her soul spirit is reunited.
 * This troper wrote the "Lily is Crookshanks" as satire on the Lily=Hedwig theories, and had no idea that anybody already seriously believed it. I would have thought that if using the word "obviously" in a Pothole to Epileptic Trees didn't get the point across, the point would have been gotten by the book on cat sexing.
 * *bang* *bang* *bang* *bang* *bang* *bang*

Crookshanks Is Lily Potter

 * It was actually James's sacrifice that protected both Lily and Harry. Voldemort realised he couldn't kill Lily and instead transfigured her into a cat an unable to transform back. (ginger fur and all) he goes to kill Harry, not working and back fires because of two people that just sacrificed themselves for him, even when one was not successful.
 * Lily as a Cat wanders around until she gets put into the magic pet shop. In a pissy mood would not anyone buy her. Then the spitting image of her husband walks in, she then sees Peter and causes a commotion and lets herself be bought by Hermie to get back to Hogwarts to be with her son and to get Peter.
 * She meets with Sirius, he does not recognize her because her transfiguration was done by dark magic and unable to communicate and tell her she's Lily so Sirius comes up that she was a smart cat.
 * Voldemort does not mention it to Harry or anyone else that he didn't kill Lily, thinking it would damage his reputation more badly that he couldn't kill a Mudblood. With the fact that Crookshanks is a male, well,she was transfigured into a cat Voldemort would not have been thinking about the gender.
 * I didn't think there was any worse way to cheapen Lily's sacrifice than the Deathly Hallows theory that she was actually Hedwig, but clearly I was wrong.
 * And I suppose being forced to live as a house pet(and one in the wild for a few years) for the remainder of your life is a bed of roses?
 * *looks at my cats* Let's see... Never having to go to work or school again, having owners who love on you constantly, not having to do anything useful to earn your keep (unless you're a cat who lives in a barn, and even then, maybe)... That's just an awful life, OP; you're absolutely right.
 * I wouldn't call it a cheapening of her sacrifice, instead of losing her life, she loses her humanity. Hell, it almost adds to the sacrifice. If Lilly died, she would be able to go on to the next great adventure in Heaven. Instead she's forced to spend her remaining life as a animal knowing that her husband is dead and that an evil madmen is trying to kill her only son. Until book 3 she had to spend most of her time either wandering the forest alone, or cramped in an old pet shop. I really don't see why being happy would cheapen her sacrifice. This is a good theory, Voldemort promised Snape that he wouldn't kill Lily, but he never said anything about transfiguration!

Mad-eye Moody isn't dead.
Nobody finds his body, just his eye. Later, when Harry is going down Diagon Alley to Gringotts, they see a scarred man with a bandage over one eye.
 * What, Harry does not recognise Moody? Scars are very distinctive.
 * How scarred? Law of Conservation of Detail, y'know, and I think the original poster might be onto something (even if it is just a loose thread that probably isn't part of the final canon). If he had his face practically smashed in, or had Umbridge or a lackey gouge out his eye and take some flesh with it when he was merely unconscious, then spent the next year or however long it was living on what little he trusted wasn't poisoned, he wouldn't necessarily be recognizable.
 * Okay, but as Hermione pointed out in the book, he fell at least one mile. Even a wizard couldn't survive that kind of a fall, and that's considering that they can cast a spell to slow their descent. In order to survive a fall from that height, Moody would have had to slow his velocity down to that of a feather, which, whether or not A Wizard Did It, is probably impossible.
 * Feather Fall?
 * Um, apparition? Sure 'his wand was blasted of his hands'...but did paranoid Moody really only have one wand? Let's recap. Moody picked the person that was obviously going to leave, mid-flight, as his partner, deliberately setting himself up with no close witnesses. He then saw that he had been betrayed somehow, as the Death Eaters knew the time he was leaving, confirming his theory that the Order had been infiltrated, so he uses his exit plan. Months later, we discover just his eye. We have no one who even claims they've seen his body. The only problem with the theory is that didn't show up during the last fight...of course, he certainly knows about Polyjuice, and anyone who dies while Polyjuiced stays that way. Or he was just out of sight, we barely see the first part of the battle at all. Or maybe he just missed it.

The entire book is a lie
Harry did find the Horcruxes, but he just shot them, or blew them up in some other way. Lord Voldemort was taken out by a sniper rilfe, and the entire book is the story Harry told the Ministry just to screw with them.
 * In addition, Molly Weasley actually threw Bellatrix into a volcano and the rest of the Death Eaters were blown apart by land mines.
 * None of the characters died and everyone who has read the book does not have a massive case of Dis Continuity, Harry just told them that they died to make them feel guilty for not doing something earlier on. Or maybe Harry lost contact with them at the point where they "died," so he doesn't know what happened to them after that. So he Put Them On A Bus in the cruelest way possible, again, to screw with the Ministry.

There's a reason why Harry came back from the dead and it wasn't involving the Deathly Hallows.
The book pretty much makes it clear that the Deathly Hallows aren't all that they are cracked up to be, the invisible cloak notwithstanding. The Elder Wand is a just a stronger wand and the ring just showed ghosts of ghosts. No, what brought Harry back to life was a completely different plot element that was already explained. You see, according to the book, when Voldemort hit Harry when he was shielded by love, part of his soul broke off and went into Harry, giving him the connection/Parsletounge/etc. However, during Goblet of Fire, Harry's blood was taken in a very symbolic manner in order to facilitate Voldemort's revival. The reason why it was so symbolic and the reason why the spell was the evil Black Magic was because it was a soul stealing spell, hence Dumbledore saying that they were 'bound even closer than any wizard before them'. Because no wizarding pair in the world had one person having a part of the other's soul while the other had a part of their soul. So, long story short, when Harry is killed, he dies and so does the part of Voldemort's soul within him. But the reason he could come back to life was because part of his soul still existed somewhere. In short, Voldemort was Harry's horcrux!
 * While this is a cool idea, it is shot down by the fact that, when Harry killed Voldemort, it worked. Remember, when You-Know-Who "killed" Harry, it only destroyed the Horcrux: the bit of his soul has essentially been reduced to a suit of Plot Armor. As such, if Lord Thingy actually was a Harrycrux, Harry's bit-of-soul should've performed a similar function, and You-Know-Who should be able to return for a third time. (...Oh, great, I think I just launched a thousand Book 8 fanfics.)
 * Maybe Harry ended up killing that bit of him, along with Voldemort?
 * I originally thought this (the guess) was true. Harry is Voldemort's last horcrux, and Voldemort is Harry's only horcrux. Killing Harry destroyed the horcrux, so Voldemort had no Soul Jar left. Harry still had one (Voldemort). However, as written, there's no real reason the Killing Curse should have rebounded unless the Elder Wand said "screw you, just because you're holding me doesn't mean he's still not my master!" and intentionally won the duel for Harry (please respond if I'm incorrect in any way regarding the final duel). So it's really down to guessing whether the Elder wand was the next best thing to sentient, or Harry screwed up the casting of the curse via his Expelliarmus winning the quick-draw by just enough, since it didn't seem that clear.
 * But wasn't Nagini not killed until after Voldemort killed Harry? In which case Voldemort still had a Horcrux - Harry wasn't his last one.
 * I think this troper is talking more about the time Harry died chapters before and was brought back, not the anti-climatic duel. Of course, I could be wrong.
 * I was talking about both. When did he come back during the final duel?
 * He(Voldemort) didn't, he(troper) was talking about the Elder Wand killing Voldemort, which has nothing to do with his first sentence OR the original topic.
 * To turn this into a Humiliation Conga for Voldemort: Since the way for a Horcrux-master to destroy his is to go into a emo-storm of regret, Harry's is/was effectively immune to that-he has absolutely nothing to feel sorry about how it was created.
 * Er, is there really confusion about this? Dumbledore specifically said that Harry didn't die because Voldemort used his blood. That kept Lily's protection alive and prevented Harry from dying as long as Voldemort was still alive. It's in the chapter where Harry talks to Dumbledore in King's Cross Station. It has nothing to do with the Deathly Hallows.

Harry has a mullet.
His hair was said to be "down to his shoulders." Rule of Cool.
 * Maybe it was worn like that as a tribute to early in the book, rather than a mullet?
 * Yes. Having hair "down to your shoulders" is not how you describe a mullet.
 * Maybe it was actually a tribute to ?
 * I think that's pretty likely, actually. After all,  was "the bravest man [Harry] ever knew."
 * Or, he's been living on the run for months on end and cutting his hair hasn't really been in his top priorities. Crazy theory, I know. (Also, in response to above, wasn't dead yet when Harry's shoulder length hair is discussed. And Harry still thinks he's an evil SOB at that point, too.
 * Um, yes he was. The "hair down to his shoulders" description is from the epilogue.  is cold in his grave by that point.
 * Actually there is a scene describing Harry's shoulder length hair when he see's himself in the mirror for the first time in months when he is at Malfoy Manor after being captured by Snatchers.

Snape knew that Voldemort was going to kill him.
He just didn't expect him to do it with the snake. His reaction to being told he was going to be killed was pretty atypical for someone who wasn't expecting it, even if he knew it was an occupational hazard of being a spy and a Death Eater. Also, there's the question of what if Snape had survived the battle? He had a very good chance of being killed by someone because he killed Dumbledore and never getting a chance to explain why. So in a way, he not only expected to die, he might have, in the deepest recesses of his mind, wanted to. (I can't see Snape living comfortably in the Muggle world, can you?)
 * DD knew that Snape would die in the Shrieking Shack in June, while Harry was in the cellar. It was essential for DD's Thanatos Gambit that Riddle kill Snape in that exact time, place, manner so that Snape could give Harry the Info Dump.

Potter Puppet Pals is canon, and is a puppet show shown while Harry's kids are at school.
Obviously made by George's misfit child, Niel "Ciecaraga" Weasly, this show was a satire on the books. He was expelled for how offensive it was to victims of the Second Wizarding War, mocking their heroes and potraying Voldemort as sympathetic. Even Fred was ashamed in the afterlife.
 * Hagrid doesn't get why the "rub meat in your hair" cure for wizard lice is funny, and Neville is less than pleased at being portrayed as a squash.

If Ron hadn't have broken up Harry and Ginny's kissing at the Borrow, they would have had sex.

 * If the number of Weasley kids who exist are any indication of Molly's sex drive, then Ginny is probably a horny one when she's ovulating.
 * Of course Ron saved Harry's life then. If Ginny got knocked up then, Babies Ever After kicks in, possibly bringing us a Birth-Death Juxtaposition when Harry dies during the Battle of Hogwarts as Ginny gives birth.
 * On the other hand, that may have also been Harry's only chance to get laid. Ever.
 * That must have been one hell of a cabbage patch, then, if Harry and Ginny managed to find kids that looked so much like them.
 * The former troper rather meant that Harry had a good chance to die WAY before that. Going against a band of murderers and their superpowered boss tends to hold that risk. Hell, he was SUPPOSED to die, just had the luck to come back.
 * "Luck," nothing. Dumbledore flat-out told Harry that he could choose not to go back, knowing full well that Harry wouldn't chicken out.
 * It's not a guess, it's the truth. From the references to time spent in lonely parts of the school grounds, it's pretty clear that they had already made out, so when she was "kissing him as she had never kissed him before", it's pretty obvious that they would have had sex. I like to think that Ron didn't really interrupt them, and JKR showed it because children read the book. It would have worked very well in the plot for Harry and Ginny to have consummated their relationship before Harry sets out on his quest.

Teddy Lupin, under the light of the full moon, will morph into a wolf, but will have fur of any wacky color of his choosing.
Well, we already know he inherited his mothers metamorphegus abilities, despite the fact that such powers are supposed to be very rare and only show up every few generations or so. Lupin had a feeling that his son would be "like him" (a werewolf). The combination of shape-shifting genes from both parents increased his odds of having shape shifting abilities. He would end up with both, due to the Rule of Cool.
 * So...Teddy is a were-sparkledog?
 * Actually, Teddy Lupin can change into a wolf (father) whenever he wants (mother).
 * Best theory ever! This could be a spinoff series.

Ted Remus Lupin is capable of reforming his entire head more or less into a wolf's, along with the typical slight changes available to a metamorphmagus.
The same as the above guess, with even more Rule of Cool applied. And when he died in battle toward the end of his prime adulthood, he was sent to the Soul Society.

Hans Landa and Dolores Umbridge are related.

 * Did you SEE the elavator scene? Compare it to Landa's entrance in the restaurant.
 * Does this mean that Hans Landa was a wizard?

Harry was not technically a Horcrux
That is, the book is right, he does have part of Voldemort's soul in him, but the actual Horcrux spell was not done, obviously. This is the reason why the Killing Curse can take out that part of Voldemort's soul, when it presumably wouldn't work on any other Horcrux. (Surely, someone tried using it.) The actual Horcrux spell, whatever you have to do besides a murder, protects the soul fragments from getting killed that.

Harry Potter was never the master of the Elder Wand.
Draco Malfoy was the master, wand ownership transfers only with magical defeat, and perhaps also non-magical murder in the case of the Elder Wand, but not via physical wand grabbing.

So why did the Elder Wand not kill him? Because it was facing another wand also owned by its master. It was Draco's wand vs. Draco's wand, and the Elder Wand realized that first (It seems more sentient than other wands) and gave up.

The fake locket counted as a piece of clothing.
And Harry freed Kreacher by giving it to him, which explains why Kreacher was at Hogwarts even though Harry never ordered him to go there.
 * Brilliant! Maybe Kreacher was so nice to Harry and Co. because he was free!

While Luna Lovegood was imprisoned in Malfoy Manor, she and Draco fell in love.
And Malfoy was totally planning on breaking her out before Harry Potter and Co. Interupted him!

Peter Pettigrew totally wanted to kill Harry Potter

 * The reason he hesitated was because he wasn't sure if he would be punished because Voldemort reserved the right to kill Harry himself. He thought he'd be okay since he'd be preventing Harry from escaping, but the instant he tried he was choked to death for betraying his master's direct orders.

The Tale of the Three Brothers is real.
Sure, Xenophilius offered the alternate theory that the three brothers were just very powerful magicians who made their own cloaks and wands and rings, but it doesn't quite gel with what we know about the magic in the series already.

1. The Elder Wand: We've been told time and again that wands are only as good as the wizard who uses them, and the real power comes from the wizard who wields the wand. So why suddenly is there a wand which miraculously makes peoples' magic stronger? Unless there's something about crafting wands which was forgotten in the hundreds of years since the Elder Wand was made, then it has to have come from somewhere else, and since it couldn't have been another wizard, Death is as good an explanation as any.

2. The Ring: This is literally the only item we've come across which can do this. The Priori Incantatem spells are after images of old spells, Voldemort's appearances are all linked to his soul, because he wasn't really dead, so where exactly does this ring come from? Who has the power to bring people back from the dead, even as some sort of after-image, that stays permanently? Death. The Ring makes people stay until the user wants them to go, Priori Incantatem only lasts for as long as someone's wand is pointed at yours.

3. The Cloak: Again, we're told repeatedly that invisibility cloaks either don't make you truly invisible or don't last forever, so why is there one that makes you completely invisible and has lasted for hundreds of years?

The gist is that there must be limits that human wizards and witches can't surpass when it comes to magic, no matter how skilled they are. If Dumbledore, Grindelwald, the founders of Hogwarts and more haven't been able to replicate the efforts of three wizards despite thousands of years of magical improvements, then where did these three items come from? The story of the three brothers meeting Death must be true, there isn't another explanation.


 * Pretty much confirmed in-universe when Ron mentions that the Invisibility Cloak acts exactly as the tale describes, then Harry puts it together that he's descended from the third brother. (This becomes Hilarious in Hindsight when you realize that Harry and Voldemort are pretty much cousins seventy-times removed since Voldemort is descended of the SECOND brother) And then Dumbledore and Voldemort flat out prove the Elder Wand is real so the first brother also existed. Harry even proves the Stone is real when he uses the thing to summon his parents, Sirius, and Lupin. Since we know Voldemort's grandfather claimed direct lineage to the Peverell brothers as stated in book six and that there were three of them...well, do the math. The Peverell siblings are the three brothers in the tale and their encounter with Death happened.

The real reason Harry survived Voldemort's curse that destroyed the Horcrux within him was his mastery of the Deathly Hallows.
If the Deathly Hallows are real, then by theend of the book Harry is the master of all three -

1)He has earned and found and was the last person to use the Resurrection Stone, and even had the phantoms of his loved ones as created by the Stone with him when he was killed.

2)He owns and has in his possession the Invisibility Cloak, also given to him by Dumbledore and inherited legally from his father.

3)He has, according to the events later in the book, mastery even if not possession of the Elder Wand, which was also the wand used to kill him.

Thus he is the mastery of all 3 Hallows and according to the legend the master of Death itself. Voldemort's curse didn't kill him because he could not die. He then revokes his mastery when he rejects the Wand consciously later, presumably.

This also means that Dumbledore also had all 3 Hallows at some point, but I think not all at the same time, and he had only borrowed the Cloak.


 * Actually no. Dumbledore owned the Elder Wand, and at one point had borrowed the Cloak from James. But by the time he got his hands on the stone, Harry had had the cloak for some time. Since anyone would have been able to claim the Stone by that point one could argue Dumbledore was the 'owner' of that Hallow as well, though he later bequeathed it to Harry. Only the Elder Wand genuinely belonged to Dumbledore since he outright won it. The other two weren't truly his and he never had all three at once.

Harry got a second scar from the Avada Kedavra used to kill him in the forest.
Only instead hitting him in the forehead like the first time, Harry recalls that this shot hit him in the chest. So what does this scar end up looking like? "A Hungarian Horntail. Much more macho."

The Room of Requirement is not usable anymore.
Not because it got destroyed. It's still there, and works just fine. The problem is that we know the Room does not only work for humans, as House Elves can use it just fine. And all humans left the room, leaving it the control of sentient fire. Sentient fire wants some sort of fuel, which the Room will happily supply. Forever. ('People' are hopefully one of the conjuring exceptions the room can't do or there would be some real Fridge Horror about what would be happening in that room, as Fiendfrye is actively malicious.)

The only way anyone else is getting in if one of the five people who know this explain what happened so someone know to ask for 'a room full of things I can burn'...and then figure out how to get rid of the Fiendfrye. Which is tricky, as the only Word of God ways we know are for it to run out of fuel, or be controlled by its creator, neither of which can happen here.