Which Hogwarts subject does J.K. Rowling associate with Professor Minerva McGonagall?

J.K. Rowling associates Professor Minerva McGonagall with Transfiguration at Hogwarts.

McGonagall is introduced as the Transfiguration professor in Harry Potter and the Philosopher’s Stone. Transfiguration is the branch of magic concerned with changing the form or appearance of objects and, in some cases, living beings.

She is also the head of Gryffindor house and later becomes Deputy Headmistress and Headmistress of Hogwarts. Her teaching role is therefore only one part of her importance in the books. She is portrayed as strict, highly competent, fair-minded, and loyal to the school.

McGonagall is sometimes confused with other professors because Hogwarts subjects have overlapping magical themes. Filius Flitwick teaches Charms, Severus Snape teaches Potions for much of the series, and Defence Against the Dark Arts has a succession of teachers. McGonagall’s defining academic subject remains Transfiguration.