Harry Potter: 15 Most Powerful Wizards In The Wizarding World
9. Minerva McGonagall
You don't get to be both Dumbledore's most trusted lieutenant and his heir as the head of Hogwarts without doing a lot of things right.
McGonagall's chief power comes in the form of transfiguration: she is not only an Animagus (which she learned rather than it being a genetic gift) but also helped defend the castle in the Battle Of Hogwarts by bringing suits of armour and desks to life to fight the Death Eaters.
On top of that she defeated both of the Carrows - one through stunning, the other using the Imperius Curse. And while Snape probably wasn't trying all that hard, she also held her own against him in a duel. More importantly, she also duelled with Voldemort himself (alongside Kingsley Shacklebolt and Horace Slughorn), holding him to a stalemate. And it's testament to her skill and endurance that she survived two wizarding wars on the front-lines without a single serious injury.