Minerva McGonagall

Minerva McGonagall is a fictional character in the "Harry Potter" books written by J. K. Rowling. This character is a teacher at the school Hogwarts, and a good character in the series. She helps Harry Potter, the main character, many times in the series. She teaches "transfiguration", a type of magic where you change objects or animals into other objects and animals. At the end of the books, McGonagall becomes the school principal. Her honorary title is Hogwarts Headmistress.
When McGonagall was young she went to Hogwarts. She was in Gryffindor, a house for brave and bold students. When she got older she decided to train herself to be an "animagus", a wizard who can change themselves into an animal without a wand. She can change into a cat. Later, she became a member of the Order Of the Phoenix, an organization trained to fight evil wizards. In a quidditch match, she was hurt by a Slytherin player.
McGonagall is played by Maggie Smith in the movies.