Albus Dumbledore may have been the Leader of the Light, but that did not make him perfect. Outside of Dumbledore's poor decisions regarding Harry Potter, he also had an entire study body to think about. Yet, his choices had a way of placing every person in Hogwarts in danger. Even though he had his reasons, how many explanations can there be for sacrificing the safety of the many? But, there was still another that had a way of making Dumbledore look like a saint.
Dolores Umbridge came into Hogwarts and wrecked it upside down and backward. Umbridge redesigned the school to her liking, not caring how insane her demands became or what became of others. She didn't even need to be Headmaster to put rules in place that removed the fun from Hogwarts.
Umbridge: Attacked Hagrid
When Dolores Umbridge decided the time had come to fire Hagrid from Hogwarts, she did not do so lightly. Umbridge prepared for a battle with the half-giant with backup for herself. Umbridge was prejudice against Hagrid and was happy to be rid of him. However, Umbridge went too far with his removal.
Aurors were present to attack Hagrid at the time of his firing. However, it did not end there. Professor McGonagall stepped in to stop the attack. Yet, things did not go well for her, either. McGonagall was hit by four stunners at once and needed to go to St. Mungo's hospital.
Dumbledore: The Dementors
With escaped and dangerous criminal, Sirius Black, on the loose, the Ministry of Magic made a deal with Professor Dumbledore to place Dementors around Hogwarts for security. Since everyone thought that Sirius had been a Death Eater wanting to kill Harry, they thought the extra protection made sense.
However, the Dementors did more damage to Harry than Sirius ever did. As it turned out, Sirius was not who the students needed to worry about. On the other hand, the Dementors attacked Harry several times during his third year at Hogwarts.
Umbridge: Racism
While Umbridge was not a Death Eater, she indeed agreed with many of their ideas. However, she also takes it a step further. Voldemort held pure-blood ideologies in mind as he built his army.
Yet, he included Giants in his regiment as well, not limiting it to wizards. Umbridge was strictly against "half-breeds." She was prejudiced against Hagrid for his Half-Giant lineage. Umbridge's supremacy beliefs did not end in "Harry Potter and the Order of the Phoenix." They continued into "Harry Potter and the Deathly Hallows" when she happily interrogates Muggle-Born wizards and witches.
Dumbledore: Dangerous Events
While Hogwarts may have been considered the safest place, there was, that reputation must have begun to decline when Harry Potter started his education. Dumbledore kept the Sorcerer's Stone within the castle walls while students walked about. While the Stone was hidden behind several obstacles created by Dumbledore and fellow teachers, they were easy enough to be surpassed by first-year students Harry, Ron, and Hermione. This would not be the first time Dumbledore voluntarily placed his students in danger.
A few years later, Hogwarts would host the Triwizard Tournament, a dangerous set of events that wizards have been known to die during.
Umbridge: The Inquisitorial Squad
Umbridge formed a group before she took over as Headmistress. Mostly composed of Slytherins, the Inquisitorial Squad was invented to keep an eye on the rest of the student body. The squad was meant to make sure that no one was breaking Umbridge's rules. The group eventually broke down Marietta Edgecombe, who revealed Dumbledore's Army to Umbridge. In the film, Cho Chang is the one to betray the group.
The knowledge of Dumbledore's Army was enough to remove Dumbledore from the Headmaster's position as Umbridge stepped up to receive the title.
Dumbledore: Kept Hogwarts Open When The Chamber of Secrets Opened
Throughout Harry's second year at school, Muggle-borns were being attacked and petrified. Hermione Granger, Colin Creevy, Justin Finch-Fletchley were three of the students to be attacked during the year. Yet, Dumbledore kept the school open, giving the Heir of Slytherin more chances to hurt others as well.
While keeping Hogwarts open may have been a better alternative for Harry than going back to the Durselys, a majority of other students likely would have preferred a guarantee of safety by being at home. Dumbledore later cancels all exams in the aftermath of Harry killing the basilisk.
Umbridge: The Decrees
Dolores Umbridge's rules were bizarre. From boys and girls not within six inches of each other to students may not walk in groups, her paranoia ranged everywhere.
Umbridge was a set of eyes and ears for the Ministry of Magic, and Minister Fudge in particular. Fudge was desperate to convince the public that Dumbledore and Harry were lying about Voldemort's return and instead were after the Ministry and Fudge's job. Umbridge worked to prevent a rebellion against the Ministry, and the Decrees were also involved in trying to prevent clubs unless Umbridge had knowledge of the club and approved it.
Dumbledore: Detention In The Forbidden Forest
One of the first speeches Dumbledore gives includes avoiding going into the Forbidden Forest because you may die a painful death. Yet, he later determines that the best way to provide students detention is to send them into the Forbidden Forest. Dumbledore's logic does not make sense, especially the way detention goes.
Hagrid splits the group up, two kids go with him, and the other two go with his dog, Fang. If Dumbledore was going to send students to the dangerous forest, he should have prepared another teacher to go with the group.
Umbridge: Tortured Students
Dolores Umbridge did not hesitate to torture her students. Detentions with Umbridge were the worst anyone could experience with help from her Blood Quills. The Blood Quills did not use ink to write. Instead, they used the blood from the person's body to write the sentence and then engraved it into their skin.
Harry is forced to write with one during detention, leaving him with "I must not tell lies." He is not the only one to receive this treatment, as several others do too. However, Umbridge also used a truth serum on students to force them to reveal their secrets to her.
Dumbledore: Let Snape Bully Students
Of all the members of his staff, Severus Snape was the most constant problem. He would insult, harm, and bully his students frequently. Complaints about the Potions Master must have reached Albus Dumbledore over the years. Or, at least, Dumbledore had to know what was going on.
Yet, Snape's place as a double agent was valuable to Dumbledore and likely because of that Snape got away with so much. Dumbledore did not punish Snape for his actions toward the students, almost as if he was deliberately looking the other way.