Severus Snape wanted to teach D.A.D.A. for years, but Albus Dumbledore denied him the job repeatedly, partly for fear of Snape straying back towards the darkness, and partly to keep him around for longer, given the curse on the position. Snape finally got his wish in Harry's sixth year, taking over D.A.D.A.
He told Harry, “You see, we have never been able to keep a Defense Against the Dark Arts teacher for longer than a year since I refused the post to Lord Voldemort.” (The Half-Blood Prince, Lord Voldemort's Request) And that's the exact reason why he kept refusing the post to Snape - he needed him too much to risk him.
In chapter 2 of Harry Potter and the Half-Blood Prince "Spinner's End," Snape reveals that Dumbledore denied him the Defense Against the Dark Arts job because he seemed to think the position would bring about a relapse and tempt him into his old ways.
Dumbledore didn't give Snape the Defence Against the Dark (D.A.D.A) job because he already suspected the post was cursed and he didn't want to lose Snape from Hogwarts. Hogwarts had not been able to keep a D.A.D.A teacher for more than a year ever since the post had been refused to Lord Voldemort, aka Tom Riddle.
While Quirell having the literal most evil wizard living on the back of his head should make him the worst Defense Againist the Dark Arts teacher, it goes to show how truly awful Umbridge is. Even with the most famous dark wizard of all time sitting in on classes, Quirell doesn't come out as bad as Umbridge.
With all that being said, there is one, just one, bad DADA professor who, as impossible as it may seem, was even worse. 6. Dolores Umbridge: Officially the worst DADA professor Harry ever had (and probably in all of Hogwarts history), we have the most despised character of the franchise, "Professor" Umbridge.
In “Harry Potter and the Sorcerer's Stone,” professor Quirinus Quirrell (Ian Hart), Harry's first Defense Against the Dark Arts teacher, is unique in that, inadvertently or not, he is also the first teacher to try to kill him.
Yes, Dumbledore did ask Snape to kill him so Draco wouldn't. Dumbledore did indeed ask Snape to kill him, so that Draco wouldn't either succeed and maim his own soul, or more likely fail and be killed by the Dark Lord for his almost inevitable failure. "All the same, try.
With the return of his Death Eaters at the end of Book Four, Voldemort declared that Snape had left their ranks forever. Conversely, Dumbledore went on declaring his undying trust in Snape. So Dumbledore was no more wrong than was Voldemort.
[Harry Potter] Professor Minerva McGonagall originally taught Defense Against the Dark Arts (DADA) at Hogwarts.
Severus Snape wanted to teach D.A.D.A. for years, but Albus Dumbledore denied him the job repeatedly, partly for fear of Snape straying back towards the darkness, and partly to keep him around for longer, given the curse on the position. Snape finally got his wish in Harry's sixth year, taking over D.A.D.A.
Harry describes Umbridge to Sirius Black, saying that she's vile enough to be a Death Eater, despite not being one. Umbridge is also depicted to be a prejudiced person, despising half-breeds and Muggle-born witches and wizards to the point of firing Hagrid due to his half-giant birth status.
“Dumbledore didn't want to lose his wand at that point and Draco disarmed him. So that meant that the wand gave Draco its allegiance, even though Draco never knew it, even though Draco never touched it. “From that moment on, that wand gave its allegiance to Draco, and it wouldn't work as well for anyone but Draco.”
Dumbledore and Grindelwald took a blood oath to not fight each other. "Fantastic Beasts: The Crimes of Grindelwald," the second film in the series, reveals that as teenagers Dumbledore and Grindelwald undertook a blood pact that wouldn't allow them to move against each other.
As mentioned in the book, Dumbledore was 'the only one he ever feared'. Deep down, Voldemort knew that Dumbledore was more powerful than him. He had superior magical capability and possessed important information about Voldemort. As they say, knowledge is power!
Nonetheless, despite her initially benevolent nature, Nagini's blood curse eventually turned her into a snake permanently. Though it is unknown if she became evil as a result of that, or was turned evil as a result of Voldemort turning her into a Horcrux. As a snake, Nagini was completely loyal to Lord Voldemort.
Voldemort, weakened by his long stint as "less than the meanest ghost' 69 insists on making one more Horcrux. And unlike with Harry, Voldemort did say the spell when he killed Bertha Jorkins to make Nagini a Horcrux.
Voldemort intentionally made six Horcruxes, but when he used Avada Kedavra on Harry, he unintentionally created a seventh Horcrux. Instead of dying, Lily's love for Harry created a counter 'curse' known as Sacrificial Protection and saved Harry.
Image via Warner Bros. Similarly to Harry, Snape's patronus represents a person. In the memories he gives Harry before his death, Snape shows Dumbledore his patronus, using the form to prove his love of Lily Potter, Harry's mother.
Knowing that Snape has been on the Dumbledore's side for all seven of the Harry Potter books reveals him as an extremely brave man and a truly skilled spy. Snape has had to face and deceive the terrifying Lord Voldemort constantly.
The accident that cost Lockhart his sanity occurred at the end of his year at Hogwarts, when he was hit by a backfiring Memory Charm that forever erased his past. He has since resided in the Janus Thickey Ward of St Mungo's Hospital for Magical Maladies and Injuries.
Horace Slughorn, a former teacher who himself had taught Snape during his Hogwarts years, comes out of retirement and replaces him as Potions Master. With Snape no longer teaching Potions, Harry enrols in Slughorn's class and is lent an old textbook until his new one arrives.
Personality. Gilderoy Lockhart was an immoderately vainglorious, self-obsessed, egocentric, and narcissistic self-promoter who claimed to have accomplished multiple heroic deeds. However, in reality, he was nothing but a charlatan who took credit for other Wizards and Witches' achievements.