Dolores Umbridge

Professor Umbridge, the main antagonist in Harry Potter and the Order of the Phoenix, was a professor who taught at the Hogwarts School of Witchcraft and Wizardry. She worked for the Ministry of Magic and the Minister himself, Cornelius Fudge.

Order of the Phoenix
Umbridge's first appearance in the film took place at Harry Potter's hearing, to address his violation of the Under-Age Restriction of using magic outside of school. He had performed a Patronus charm in the presence of a Muggle (non-magic fellow) to defend himself against the two dementors he and his cousin Dudley were confronted with, which Harry had explained later. Various members of the Ministry, including Fudge and Umbridge, believed that the presence of dementors in Privet Drive was impossible, since the Ministry controlled their locations. The very reason for this occurrence, was the return of the Dark Lord, but Fudge refused to change his mind about the boy. The vast majority of the crowd were in favor of clearing Harry of all charges, not including Umbridge.

When Harry Potter began his first day of his fifth year at Hogwarts, he discovered that Umbridge was appointed as the Defense Against the Dark Arts teacher. Throughout the story it became more clear that the Ministry was interfering at Hogwarts. Later she was made the High Inquisitor of Hogwarts, giving her the power to enforce new rules and dismiss teachers. At a time, she inspected every professor, and attempted to banish Professor Trelawney from Hogwarts permanently.

To escape Professor Umbridge's restriction from using magic in her class, Harry and his friends created a secret organization of students, called "Dumbledore's Army" to improve skills of using magic for defense. Umbridge was the one to catch them, and brought them to Albus Dumbledore, the headmaster of Hogwarts. After Dumbledore admitted that he was responsible, Fudge requested Dumbledore's immediate sentence to Azkaban to await trial. When Dumbledore escaped, Umbridge became the new headmaster, and she gave a painful detention to all the students who took part in the secret organization.

Dumbledore's secret weapon
Umbridge knew that Harry Potter was the main offender of her rules, and that he deserved to be punished. In front of several Hogwarts students, she attempted to perform the Cruciatus Curse on Harry. Before she did, Hermione Granger cried out stopped Umbridge. She told her about Dumbledore's secret weapon, which didn't actually exist. Hermione led her with Harry into the Forbidden Forest, a location which, forbidden to students, contains monstrous creatures and dark alleys. After Umbridge realized she was being played upon, centaurs captured her. This was her last appearance in the fifth book.