Professor Minerva McGonagall teaches Transfiguration in J.K. Rowling’s Harry Potter novels.
Transfiguration is the magical discipline concerned with changing the form or appearance of an object, creature, or person. McGonagall is introduced as the strict but fair Transfiguration teacher and later becomes head of Gryffindor House and deputy headmistress of Hogwarts.
The subject is different from Charms, which generally adds or changes properties without transforming an object’s basic nature. It is also distinct from Potions, taught by Severus Snape and other professors, and Herbology, taught by Pomona Sprout. These neighboring subjects are a common source of mix-ups when identifying McGonagall’s role.
McGonagall is an Animagus who can transform into a tabby cat. That ability is related to transformation, but it does not mean her subject is Animagus studies; no such standard Hogwarts class is established in the novels.