Dolores Umbridge
Background
Dolores Jane Umbridge is the Undersecretary for the Ministry of Magic.
During the events of Harry Potter and the Order of the Phoenix (2007) played by Imelda Staunton
Harry Potter's trial starts and Albus Dumbledore arrives just in time after not being told the trial would start early. Harry tells the Wizengamot, which includes Dolores and Amelia Bones, that he used magic to fight against the Dementors in order to save Dudley Dursley. Mrs. Arabella Figg takes the stand and describes the Dementors. A vote is taken and Harry is cleared of the charges.
During the Hogwarts banquet, Dumbledore welcomes back Professor Grubbly-Plank as the Care of Magical Creatures while Hagrid is away. He then introduces Dolores as the new Defense Against the Dark Arts teacher. Dolores interrupts Dumbledore and tells the students that the Ministry of Magic is very concerned about their education. In class, Parvati Patil watches as Padma Patil levitates a paper bird and sends it flying around class. Dolores destroys the paper bird and then tells the class that she will focus on teaching them to pass the Ordinary Wizarding Levels or OWLs. Dolores tells the class that the idea that Voldemort is alive is a lie and as Harry argues with her, orders Harry to see her after class for detention. For detention, Harry is forced to write "I must not tell lies" using a special quill, and as he does, the words are etched into his hand.
Dolores and Professor McGonagall have an argument about Harry's punishment and Dolores declares that things at Hogwarts are worse than the Ministry thought. Mr Filch posts a decree stating that Dolores has been appointed as the Hogwarts High Inquisitor. Dolores starts to questions the professors and creates increasingly more and more decrees including the banning of all Weasley products. As she is monitoring Professor Flitwick and the choir perform, she uses a measuring tape to measure Flitwick. She asks Professor Sybil Trelawney to predict something and Trelawney tells her that she is in grave danger. Trelawney is fired by Dolores and Dolores has Filch bring Trelawney's things out to the courtyard. Dumbledore walks out into the courtyard and has McGonagall bring Trelawney's things back inside and tells Dolores she can only fire professors, not expel them from Hogwarts. Dolores sees Harry and the others walking back to Hogwarts and makes a decree that all student organizations are banned. After Finch continues to fail at finding their secret hideout, a student Inquisitorial Squad is created and Draco Malfoy, Crabbe and Goyle join it.
During one of Dumbledore's Army's training sessions, they are caught by Dolores, Filch and the student members of the inquisitors. Percy Weasley drags Harry and Cho Chang, who told the location of the training session, to the meeting with Fudge, Kingsley Shacklebolt, Dawlish and Dolores in Dumbledore's office. They accuse Dumbledore of forming an army to revolt against the Ministry. Fudge orders Kingsley and Dawlish to take Dumbledore to Azkaban and Dumbledore escapes with the help of Fawkes. Dolores replaces Dumbledore as head of Hogwarts and all members of Dumbledore's Army are required to go to detention where they are forced to experience the same abuse as Harry was. During the year 5 OWL exam, Fred and George burst into the exam room and quit school while also creating a fireworks display that destroys all of Dolores' framed decrees.
Harry, Ron and Hermione go into Dolores' office to use her chimney flue. They are caught by Dolores and the student inquisitorial squad. Dolores tells Professor Snape to bring her truth juice, but he tells her that she used the last of it on Cho. Dolores is about to use the Cruciatus Curse on Harry when Hermione tells her that they know where Dumbledore's secret weapon is hidden. Harry, Hermione and Ron take her to the Forbidden Forest where they encounter a group of Centaurs. Dolores insults the Centaurs and one of them fires an arrow at her. She retaliates by casting a spell which causing an ever tightening rope to strangle the Centaur. Grawp grabs and lifts up Dolores and the Centaurs encircle Grawp and he gives Dolores to the Centaurs. Later, he Daily Prophet reports that Harry has been vindicated, Dumbledore has been reinstated and Dolores has been suspended.