1. These were some of the original names of the characters before Rowling changed them: Hermione Puckle, Neville Puff, Draco Spinks, Lily Moon (Luna Lovegood), Madhari Patil, and Mati Patil.
2. Fred and George were born on April Fool's Day.
3. The only time the Weasley twins were ever apart were when George's ear was cursed off and when Fred was killed.
4. George Weasley married Angelina Johnson and had two kids named Fred and Roxanne.
5. Fred and George once threw snow at Voldemort's face.
6. Remus Lupin's Patronus is a wolf (not a werewolf), because all things wolf-related disgust him.
7. His father, Lyall Lupin, once described werewolves as "soulless, evil, deserving nothing but death" in front of Greyback, and he took his revenge by biting Remus just before his fifth birthday.
8. Lupin was posthumously awarded the Order of Merlin, First Class, the first werewolf to ever receive this honor.
9. Nymphadora Tonks' original Patronus was a jack rabbit, but it eventually changed to a wolf.
10. Minerva McGonagall was a gifted Quidditch player, but she experienced a nasty fall in her final year at Hogwarts that left her with a concussion and several broken ribs.
11. After graduation, Minerva fell head-over-heels in love with a Muggle boy named Dougal McGregor.
12. He proposed to her, and although she wanted to accept, she declined in fear of never being able to reveal her true identity unless they had kids. If she broke the International Statute of Secrecy, she would lose the job at the Ministry for which she was giving him up.
13. Minerva left for London three days later, and found herself bitter from heartbreak and hating her new life. She eventually took a teaching post at Hogwarts.
14. Professor McGonagall ended up marrying her old boss at the Ministry, Elphinstone Urquart, who proposed several times before she accepted.
15. Her husband suffered an accidental death (Venomous Tentacula bite) three years into their marriage. She always kept her maiden name.
16. The Death Eaters' Dark Marks eventually faded into scars. They no longer burn or hurt.
17. Dementors are based off J.K. Rowling's time of depression in her twenties.
18. Rowling said the Harry Potter series might not have happened if her mother hadn't died. "The books are what they are because she died ... because I loved her and she died."
19. Rowling almost killed off Ron "out of sheer spite."
20. Michael Jackson once approached Rowling about making a musical based on the books, but she turned it down.
21. However, a play about Harry's life pre-Hogwarts is hitting the London stage in 2015.
22. For a long time, Rowling planned the last word in the series to be "scar," but eventually changed the last sentence to "All was well."
23. Voldemort was 71 years old when he died in the Battle of Hogwarts.
24. Dumbledore fell in love with Gellert Grindelwald.
25. Snape was not immediately added to the portraits in the headmaster's office, but Harry insisted he be placed next to Dumbledore.
26. Most Black family members are named after stars or constellations. (Sirius is known colloquially as the "Dog Star," reflecting its prominence in its constellation, Canis Major (Greater Dog).
27. A magnificent fountain in the middle of the park at Beauxbatons School is said to have healing and beautifying powers and is named for Nicolas and Perenelle Flamel.
28. Luna Lovegood became a naturalist and eventually married Rolf Scamander, with whom she had twin sons, Lorcan and Lysander.
29. Professor Quirrell was technically a temporary Horcrux, as were the animals Voldemort inhibited during his years of exile.
30. Arthur Weasley was supposed to die in Harry Potter and the Order of the Phoenix, but was replaced with Sirius.
31. Ginny Weasley became a professional Quidditch player for the Holyhead Harpies, but eventually retired to take care of her children.
32. She then became the senior Quidditch correspondent for the Daily Prophet.
33. James Sirius Potter, Harry's oldest son, stole the Marauder's Map from his dad's desk.
34. Harry, Ron, and Hermione all got their own Chocolate Frog cards.
35. Herpo the Foul was the first person to create a Horcrux and the first person to breed a Basilisk.
36. Winky the house-elf is still at Hogwarts, but never got over her addiction to Butterbeer.
37. Harry and Dudley would still see each other after the Battle of Hogwarts, but they would visit more out of a sense of duty and sit in silence so that their children could see their cousins.
38. Hermione began her post-Hogwarts career at the Department for the Regulation and Control of Magical Creatures to help improve the lives of house-elves, but then moved to the Department of Magical Law Enforcement.
39. Ron became an Auror, but at some point, he also helped George at Weasleys' Wizard Wheezes, which became a booming business.
40. The tale of the Deathly Hallows was based on The Pardoner's Tale by Geoffrey Chaucer.
41. Remus was killed by Antonin Dolohov and Tonks was killed by Bellatrix Lestrange.
42. There are 700 fouls in Quidditch.
43. After a disappointing defeat against Egypt in 2002, "a tearful [Viktor] Krum announced his retirement" from Quidditch. He returns this year for the 2014 Quidditch World Cup.
44. Cho Chang married a Muggle.
45. All the fractioned platforms at King's Cross Station are in use for Wizards and Witches.
46. Platform 7 1/2 is the Orient Express.
47. Aunt Marge was in love with her neighbor Colonel Fubster, but he would never marry her because of her horrible personality. This unrequited love is part of the reason she's so mean and bitter.
48. She also asked him to drown one of her pups once because it was a "weak," "underbred", "ratty little thing."
49. Draco Malfoy almost attended Durmstrang Institute, but his mother didn't want him to be so far away from home.
50. The Vanishing Cabinet makes its first appearance in Harry Potter and the Chamber of Secrets.
51. The third smell Hermione recognizes in the Amortentia potion is Ron's hair.
52. Dumbledore's boggart is the corpse of his sister, Ariana.
53. Before taking the post of Defense Against the Dark Arts, Quirrell was the Muggle Studies teacher.
54. Firenze the Centaur was eventually welcomed back to his herd.
55. Rowling killed Hedwig because it represented the loss of innocence and security, and her fate marked the end of Harry's childhood.
56. If Dumbledore had a Muggle song playing at his funeral, Rowling said it would be "My Way" by Frank Sinatra.
57. Two alternate titles for the final book were Harry Potter and the Elder Wand and Harry Potter and the Peverell Quest. She quickly decided against the latter because it sounded too corny.