Fantasy Literature

Mafilda Hopkirk from the Improper Use of Magic Office sent Harry an official warning letter after he performed the Patronus Charm to save Dudley and himself from Dementors. Dolores Umbridge was at Hogwarts, Fudge was the Minister, and Arabella Figg was a neighbor, not Ministry officials.

The Half-Blood Prince (Severus Snape) invented Muffliato (fills ears with buzzing), Sectumsempra (causes deep wounds), and Levicorpus (hangs victim upside down by ankle). Alasto momentum and Episkey are standard spells not created by Snape.

Voldemort forced Kreacher the house-elf to accompany him to the cave where he placed the locket Horcrux. Kreacher was made to drink the potion and nearly died, but survived by returning to the Black family home. Snape, Bellatrix, and Nagini were not involved in this specific task.

In Harry Potter and the Goblet of Fire, Moaning Myrtle helped Harry by telling him the merpeople live in the lake bottom and giving him directions during the Second Task. Mad-Eye Moody was actually Barty Crouch Jr. in disguise, Cedric didn't help with this, Dumbledore set up the task, and Hagrid was not involved.

Neville Longbottom became the Herbology Professor at Hogwarts after the Second Wizarding War. This is revealed in the epilogue of Deathly Hallows and confirmed by J.K. Rowling. Hermione worked in the Department of Magical Law Enforcement, Luna became a magizoologist, and Harry became an Auror.

Snape killed Dumbledore at Dumbledore's own request, as part of a carefully planned arrangement to spare Draco Malfoy from having to commit murder and to protect Snape's cover as a Death Eater. Dumbledore was already dying from the curse of Marvolo Gaunt's ring, and he asked Snape to end his suffering when the time came.

Severus Snape's Patronus is a silver doe, which is the same form as Lily Potter's Patronus. This reveals that Snape's love for Lily never died, and his Patronus remained hers even after her death. Harry followed this silver doe to the Sword of Gryffindor in the Forest of Dean during the Deathly Hallows mission.

Bellatrix Lestrange killed Sirius Black during the Battle of the Department of Mysteries in Order of the Phoenix. She hit him with a Stunning Spell that caused him to fall through the Veiled Archway in the Death Chamber, which resulted in his death. This was a devastating moment for Harry, as Sirius was his godfather and closest connection to family.

Voldemort used Kreacher, the Black family house-elf, to test the magical protections in the sea cave where he hid the locket Horcrux. Kreacher was forced to drink the potion in the basin, which caused him terrible suffering, and then Voldemort left him there to die. Kreacher was later able to escape using house-elf magic and return to Regulus Black.

Draco Malfoy became the true master of the Elder Wand when he disarmed Dumbledore on the Astronomy Tower, right before Snape killed Dumbledore. Even though Dumbledore arranged his death with Snape, Draco's disarming spell overcame Dumbledore's defenses, making Draco the wand's master according to wand lore. Voldemort never understood this, which is why the Elder Wand failed him during his final duel with Harry.

Teddy Remus Lupin is Harry's godson, the son of Remus Lupin and Nymphadora Tonks, who were both killed during the Battle of Hogwarts. Harry was named Teddy's godfather by his parents before their deaths, and Harry maintained a close relationship with him, even having Teddy live with him part-time. Albus Severus is Harry's son, not his godson, and Lily Evans was Harry's mother.

The Basilisk itself was never a Horcrux, though Harry destroyed one Horcrux (the diary) by using a Basilisk fang. The seven actual Horcruxes were: Tom Riddle's diary, Marvolo Gaunt's ring, Salazar Slytherin's locket, Helga Hufflepuff's cup, Rowena Ravenclaw's diadem, Harry Potter (unintentional), and Nagini the snake. The diadem (listed as 'Daidem') was indeed a Horcrux.

The Mirror of Erised shows the deepest desires of a person's heart. When Harry looked into it during his first year at Hogwarts, he saw his parents, Lily and James Potter, along with other ancestors. The name 'Erised' is 'desire' spelled backward, and the inscription on the mirror reads 'I show not your face but your heart's desire'. Dumbledore warned Harry that the mirror could drive people mad with obsession.

Harry loved Dumbledore the most, viewing him as a mentor and father figure throughout his years at Hogwarts, even after discovering Dumbledore's manipulations. Harry hated Snape the most for most of the series, believing him to be a traitor who killed Dumbledore, until learning the truth about Snape's loyalty and sacrifices in the final book. This answer format shows loved/hated respectively.