As JK Rowling reveals we're pronoucing Voldemort wrong, we look at the revelations that have emerged since the last book was published
1) Harry and Lord Voldemort are family
Unpleasant, yet inevitable in the small, slightly incestuous wizarding world. The key to this is Harry's Invisibility Cloak, which was left to him by his father, James, a direct descendant of Ignotus Peverell – one of the three brothers who possessed one hallow (a means to achieve immortality) apiece and became the stuff of wizarding legend.
Much as Harry and Voldemort share a prophesy and a phoenix feather in their wands, they also share the Peverells, hence why the Dark Lord was in possession of another hallow: the Resurrection Stone.
Savvy readers would have sussed this out from careful reading of Harry Potter and the Deathly Hallows, but JK Rowling confirmed that the pair are "distantly related" through the Peverells, saying: "nearly all wizarding families are related if you trace them back through the centuries" in a web chat in 2007.
2. Professor Dumbledore is gay
One of Rowling's best-received revelations, and yet also one she continues to explain and defend. Hogwarts' Headmaster came out of the closet in 2007 when Rowling was reading her final novel at Carnegie Hall, New York. According to fansite The Leaky Cauldron, Rowling got a "prolonged ovation" for announcing that Dumbledore was in love with the great, and latterly dark, wizard Grindelwald.
Now the stuff of Potter legend, Rowling said that this character trait was news to even the Potter film scriptwriters, adding: "If I’d known it would make you so happy, I would have announced it years ago!'"
3. Ron and Hermione need marriage counselling
This one really set the Crookshanks among the pigeons, and sparked a media frenzy after being published on the front page of The Sunday Times. In an interview with Emma Watson for Wonderland magazine in February 2014, Rowling said: "I wrote the Hermione/Ron relationship as a form of wish fulfilment. That’s how it was conceived, really. For reasons that have very little to do with literature and far more to do with me clinging to the plot as I first imagined it, Hermione ended up with Ron.
"I know, I’m sorry, I can hear the rage and fury it might cause some fans, but if I’m absolutely honest, distance has given me perspective on that. It was a choice I made for very personal reasons, not for reasons of credibility.
"Am I breaking people’s hearts by saying this? I hope not."
Ron and Hermione's triumphant kiss during The Battle of Hogwarts inspired thousands of 'fanfic' authors and artists, and in the epilogue to the final novel the pair send their oldest child off to Hogwarts. However, fans were divided over whether the highly intelligent Hermione would be happy with the more prosaic Ron, including Watson herself, who said: "I think there are fans out there who know that too and who wonder whether Ron would have really been able to make her happy."
But the full transcript showed Rowling backtracking a little, saying: "Maybe she and Ron will be alright with a bit of counseling, you know. I wonder what happens at wizard marriage counselling? They’ll probably be fine. He needs to work on his self-esteem issues and she needs to work on being a little less critical."
4. Rowling thinks it's wrong that girls love Draco Malfoy...
Mere months had passed since that bombshell when Rowling dropped another: she was "unnerved" by the enormous number of teenage fans in love with Hogwarts villain Draco Malfoy.
She wrote in a series of festive updates on Pottermore: "I have often had cause to remark on how unnerved I have been by the number of girls who fell for this particular fictional character.
"Although I do not discount the appeal of Tom Felton, who plays Draco brilliantly in the films and, ironically, is about the nicest person you could meet."
Rowling explains that although "girls are very apt to romanticise" the "dark glamour of the anti-hero", she writes that she has had to tell fans, "rather severely, that Draco was not concealing a heart of gold under all that sneering and prejudice and that no, he and Harry were not destined to end up best friends."
5. ...And his parents disapproved of Draco's wife
Life-long Death Eaters Lucius and Narcissa Malfoy had fallen from their lofty perch in Voldemort's inner circle - firstly after Draco's father failed to capture Harry in the Ministry of Magic, then after testifying against their former friends after the Battle of Hogwarts.
However, their obsession with pure-blood wizarding ancestry lived on, which meant they disapproved of Draco's wife, Astoria Greengrass, who wasn't a member of the "sacred 28" wizarding families. Although as "a fellow Slytherin who had gone through a similar conversion from pure-blood ideals to a more tolerant way of life" she was well-suited to Draco, family meetings were "often fraught with tension". Rowling wrote on Pottermore.
6. The Longbottoms remain in hospital for the rest of their lives
Among the saddest victims of Voldemort's reign of terror were Neville Longbottom's parents, Alice and Frank, who were former members of resistance group The Order of the Phoenix who were tortured by Bellatrix and Rudolphus Lestrange. We meet them in Harry Potter and the Order of the Phoenix, in St Mungo's Hospital for Magical Maladies and Injuries.
In interviews given to NBC in 2007, Rowling explained that Frank and Alice never recover: "I know people really wanted some hope for that, and I can quite see why because, in a way, what happens to Neville's parents is even worse than what happened to Harry's parents. The damage that is done, in some cases with very dark magic, is done permanently."
However, life improves for Neville: his grandmother finally accepts him as a talented wizard, and he gains street cred among his fellow Hogwarts alumni after marrying Hannah Abbott and living with her above Diagon Alley drinking hole The Leaky Cauldron and is appointed the new Herbology Professor.
7. Dolores Umbridge was based on a real person
There is little more fearsome than Dolores Umbridge, the Hogwarts professor and Ministry snitch with a fondness for kittens and student-torture, than a real version of her. However, one - or rather two - actually exist, as Rowling revealed in 2014.
In a 1,700 word essay, Rowling shed light on the real person who inspired the character, "whom I disliked intensely on sight. The woman in question returned my antipathy with interest.
Why we took against each other so instantly, heartily and (on my side, at least) irrationally, I honestly cannot say." However, she didn't disclosed the person's name. The author also revealed that that Umrbridge was as unappealing at Voldemort, writing: "her desire to control, to punish, and to inflict pain, all in the name of law and order, are, I think, every bit as reprehensible as Lord Voldemort’s unvarnished espousal of evil."
8. Ron and Arthur Weasley were almost killed off...
Rowling had made a promise to herself to keep the "Golden Trio" complete throughout all seven books. However, she came close to breaking it when she "wasn't in a very happy place" in her own life half-way through the series.
She told Daniel Radcliffe in an interview extra for the Harry Potter and the Deathly Hallows: Part 2 DVD: "I started thinking I might polish one of them off. Out of sheer spite. 'There, now you definitely can't have him any more.' But I think in my absolute heart of heart of hearts, although I did seriously consider killing Ron, [I wouldn't have done it]."
Ron's father, Arthur, nearly didn't survive his attack from Voldemort (in snake-form) in the Ministry, either. Rowling had to kill at least one of the Weasleys, she said, because it was unrealistic that all nine of them would survive. But she kept Arthur because "there were very few good fathers in the book. In fact, you could make a very good case for Arthur Weasley being the only good father in the whole series."
9. ... but Tonks and Lupin nearly survived
But while Arthur survived, Rowling still "wanted to kill parents" in the final novel to create "an echo of what happened to Harry just to show the absolute evil of what Voldemort's doing.” Those parents were newlyweds Tonks and Remus Lupin.
"I think one of the most devastating things about war is the children left behind,” Rowling said. “As happened in the first war when Harry's left behind, I wanted us to see another child left behind. And it made it very poignant that it was their newborn son."
10. Dudley and Harry reunite
In vaguely more optimistic news, Dudley Dursley is able to get over his parents' vitriolic treatment of Harry and spend time with him as an adult, something dozens of fanficcers had already predicted.
During an American book tour in 2007, Rowling said "Harry and Dudley would still see each other enough to be on Christmas card terms, but they would visit more out of a sense of duty and sit in silence so that their children could see their cousins."
11. Harry and Ron never graduated...
After the Battle of Hogwarts, Hermione naturally returned, sat her NEWTS and did fantastically well before boarding the Hogwarts boats back across the lake in the return of the journey First Years make. ("She would be glad to go back to school, be glad to get back to study, and then would join them at the Ministry.")
But Harry and Ron, Rowling explained in a 2007 interview with Pottercast, didn't bother: "Ron was really done with schooling. It would be kind of tempting to go back just to mess around for a year and have a break."
12. ...But managed to get fancy Ministry jobs regardless
After battling Voldemort like clockwork on an annual basis during their teens, Ron and Harry had more than adequate training to go into the Auror department of the Ministry - the wizarding equivalent of MI5.
Rowling said: "He's needed. Kingsley [Shacklebolt, Minister of Magic] would've wanted Ron, Neville, Harry and they would've all gone, and they would've all done the job. And I think that that would've been a good thing for them, too."
"Because to go through that battle and then be religated to the sidelines, I think they would've felt a need to keep going and finish the job. So that would've been rounding up, really, the corrupt people who were doing a Lucius Malfoy and trying to pretend that they weren't really involved."
13. You can find Harry, Ron and Hermione on the Chocolate Frog cards
During her 2007 American book tour, Rowling let fans in on one of the loveliest secrets of the post-Potter world and Ron's personal "finest hour" - one of the first things we learn about him is that he's an avid card collector.
Harry is described as "the first and only known wizard to survive the Killing Curse, most famous for the defeat of the most dangerous dark wizard of all time, Lord Voldemort" while Ron gets a nod for "destroying the Horcruxes and subsequent defeat of Voldemort and revolutionising the Ministry of Magic." Hermione is described as the "brightest witch of her age", who "eradicated pro-pureblood laws" and campaigned for "the rights of non-human beings such as house-elves."
14. Dumbledore could sometimes see Harry underneath his invisibility cloak
Ever suspect that Dumbledore knew Harry was at some of his most secret meetings? That's because he did. Rowling said he could silently use the incantation "homenum revelio" to see him.
15. Harry made sure that Professor Snape was remembered at Hogwarts
One of the final Harry Potter lines printed was: "Albus Severus, you were named for two headmasters of Hogwarts. One of them was a Slytherin and he was probably the bravest man I ever knew."
So it makes sense that Potter, the only person to witness Snape's selfless act, made sure that a portrait of the wrongfully scorned headmaster was installed at Hogwarts. Rowling explained in a webchat: "I like to think that Harry would be instrumental in ensuring that Snape’s portrait would appear there in due course."
16. We've all been pronouncing 'Voldemort' wrong
Eighteen years, 18 years, we've been pronouncing Voldemort's name wrong for 18 years. Rowling only admitted in September, 2015 that she always intended the 't' of Voldemort to be silent - and that she was pretty sure she was the only person who pronounced it as such.