Professor Minerva McGonagall, Dark Green Robe, Black Hat with Dark Tan Hair, Azure Circle Symbols

Comes in 2 sets, made of 4 parts. The lowest-priced set it comes in is 76382 Hogwarts Moment: Transfiguration Class (RRP £24.99).

Check the minifigures carefully when buying a used set: they're part of its grade.