McGonagall is described as a tall, rather severe-looking woman, with black hair typically drawn into a tight bun. She wears emerald green robes, a pointed hat, and always has a very prim expression.She is Deputy Headmistress, head of Gryffindor House, Transfiguration professor, and later Headmistress at Hogwarts.She has a fondness for tartan, and her handkerchief, dressing gown, and dress robes are patterned with it.She promises Harry she would do everything in her power to help him to achieve his goal of becoming an auror, and she keeps her promise.After the death of Dumbledore at the hands of Snape in Half-Blood Prince, she becomes the acting Headmistress of Hogwarts. However, in the series finale, she does not become headmistress at the start of term as expected; Snape is appointed by new Minister of Magic. At the end McGonagall takes charge of the school again and proceeds to secure it against Voldemort to ensure Harry can fulfil his mission from Dumbledore. She also organises the evacuation of the school's under-age students to ensure their safety.