I've been rereading the Harry Potter books, and I'm currently on the Order of the Phoenix. I've renewed my hatred for Dolores Umbridge. *This will contain some spoilers of the Harry Potter series, but if you haven't read/watched them yet, please get on that.*
Yes, Lord Voldemort is the baddie who we all want to see defeated in the end, but boy oh boy, does Dolores Umbridge rub me the wrong way. She is such a horrid character, but I love her portrayal in the movies (oddly)! Imelda Staunton does a marvelous job with her, and the character is written a lot better than others in the adaptations *cough* Ginny *cough*.
In grade school, I loved my classes. I was never one of the kids that said lunch was their favorite class, but then I think of Umbridge, and I understand why people would say that.
We are meant to trust our teachers, from kindergarten all the way through college and grad. We're supposed to be able to go to them with any problems, and they were supposed to help us as best they can.
In Umbridge, from the get-go, we know she isn't going to be that kind of teacher for us. In Harry's trial, she fights back as Dumbledore makes the claims about the dementor's attack. I think we're disposed to hate anyway who disagrees with Dumbledore. But then again, she is the one who orders the attack, so it makes sense that she would fight against the truth coming out.
When she's at Hogwarts, she changes things. She punishes Harry by having him cut into his hand with a bewitched quill. She disbands Quidditch. She favors Draco Malfoy. And then, she kicks Trelawney out. And while Trelawney is weird, she's lovable, and shouldn't be kicked out.
While Voldemort takes joy out of causing people pain, we know we aren't supposed to trust him. We want to trust Umbridge but she is just so slimy and so vicious. She takes pleasure from hurting the students.
And we can't do anything about and for the most part, neither can Harry. At least with Voldemort, Harry can fight.