Minerva
Minerva has taught Transfiguration for a very long time. She is just as adept at handling students as complex spells. She is good at changing things into other things but as a person she is very honest. She is solid. She likes rules. It's almost ironic that the woman who teaches children how to bend the laws of physics can herself be so steady.
She isn't cold. She's strict but warm. She knows that some of her actions cause students to dislike her, but she also knows that they are very loyal. Minerva has been teaching for such a long time. She knows how to handle these things.