Minerva McGonagall

Professor Minerva McGonagall, Head of Gryffindor, Deputy Headmistress of Hogwarts, Order of Merlin, First Class , is a witch teaching Transfiguration at Hogwarts as of 1993.

Past
Professor McGonagall's past up until 1991 is identical to her canon self. It is additionally known that in 1954 she had a portrait of herself created.

1991-1992
In Summer of 1991, Professor Dumbledore asked Professor McGonagall to help protect the Third Floor Corridor (then hiding place of the Philosopher's Stone). McGonagall achieved this by creating a gigantic version of a wizarding chess set that had to be played across to progress into the next room.

McGonagall was the one to visit Doctors Daniel and Sally Granger to inform them that their daughter Hermione was a witch. She then accompanied Hermione on her first trip to Diagon Alley shopping for school supplies, and submitted all day long to Hermione's endless questions about the magical world. She enchanted a trolley to transport Hermione's numerous books, which impressed Hermione greatly, and then Apparated the two of them back to the Grangers' doorstep.

At the start of the school-year proper, Professor McGonagall became the Head of House of Hermione, as she had been Sorted into Gryffindor House, alongside Harry Potter and Ron Weasley. She also, naturally, taught them Transfiguration. It was to McGonagall that Hermione came to speak about Quirinus Quirrell's incompetence. Having known Quirrell all through his schooling, she refused to believe that he could have gotten so bad, and brushed away her complaints with a promise that he would soon get better (which, of course, he did not).

1992-1993
On Spider Day, she was teaching Transfiguration to the First-Years (showing them how to transfigure beetles into buttons) when Albus Dumbledore came to get her to assist him and the other Heads of House in greeting the unexpected Centaurs, which she did, although she stayed silent throughout. When the Acromantulas arrived together with their attack dragon, she cast a Patronus Charm and sent the Patronus to warn the other Professors still inside of the danger.

She then joined the battle, chasing the spiders who'd managed to get inside the buildings. There, among other things, she happened upon a trio of Acromantulas giving chase to Hermione Granger. She defeated the first and then Transfigured the second, Nerchog, who had just bitten Hermione, into a cushion, before blasting the third one into the wall, knocking her out. She rushed to Hermione's side, but the girl assured her she could manage on her own and McGonagall was needed elsewhere.

Some time after the Christmas holidays, McGonagall was teaching the First-Years how to transfigure rodents into goblets. Hermione Granger managed a splendid goblet and (under the new point standards) earned two points from McGonagall for it. She then told Hermione to go see Professor Dumbledore.