Professor Minerva McGonagall
from the fabulous Harry Potter series by J. K. Rowling..........
“Have a biscuit, Potter.”
" 'Transfiguration is some of the most complex and dangerous magic you will learn at Hogwarts,' she said. 'Anyone messing around in my class will leave and not come back. You have been warned.' "
… Harry witnessed Professor McGonagall walking right past Peeves, who was determinedly loosening a crystal chandelier, and could have sworn he heard her tell the poltergeist out of the corner of her mouth, 'It unscrews the other way.'
" 'He [Dumbledore] will not be single-handed!' said Professor McGonagall loudly, plunging her hand inside her robes.
'Oh yes he will, Minerva!' said Dumbledore sharply. 'Hogwarts needs you!' "
Professor McGonagall is actually not the oldest character I'll be painting, but she certainly is feisty. An accomplished witch, she is one of the only registered Animagi and can transform herself into a cat. She leads the Transfiguration department, if the head of Gryffindor house, and eventually becomes Headmaster of Hogwarts. She takes no flak from anyone, student, or teacher. But when there's a problem, she's there to offer a biscuit and give advice, and to lend her wand and fight for what's right. And she's strong - at one point she takes four stunning spells straight to the heart ("at her age!") and returns to the castle to resume her duties.
If your only brush with Professor McGonagall is the movies, read the books. Yes, Maggie Smith is fabulous and the perfect person to play the role, and I adore her. But movies leave a lot out. Read the book!
Illustration note: I actually looked up photos of Maggie Smith as Cousin Violet from Downton Abbey for clothing hints. Her black also contains purple as a nod to that character - another tough old lady! Behind her is her patronus, also a cat.