Minerva McGonagall teaches Transfiguration at Hogwarts before becoming headmistress in J.K. Rowling’s Harry Potter series. Transfiguration is the branch of magic concerned with changing the form or appearance of objects and beings.
McGonagall is the head of Gryffindor House and serves as Deputy Headmistress under Albus Dumbledore for much of the series. She is portrayed as a strict, highly skilled teacher who expects discipline while also protecting her students and supporting the fight against Voldemort.
Her Transfiguration expertise is reflected in her ability to transform into a tabby cat, making her an Animagus. The cat form is identifiable by distinctive spectacle-like markings around her eyes. Animagi are witches or wizards who can deliberately transform into animals.
After Dumbledore’s death, Severus Snape briefly becomes headmaster, followed by a period of conflict at Hogwarts. McGonagall ultimately becomes headmistress after the Battle of Hogwarts, so her teaching role and later leadership role are separate stages of her career.