Harry Potter: 15 Most Powerful Wizards In The Wizarding World

There's no finer indication of Slughorn's power than the Death Eaters' repeated attempts to recruit him to their forces. He is a master potion maker, a hugely knowledgable student of magic (including the Dark Arts), and his command of Occlumency and transfiguration are close to unrivalled. After all, human transfiguration requires absolute mastery of the magic and he's able to transform into a chair at will.

And despite his slightly bumbling appearance, Slughorn is also an impressive duellist, surviving the Battle Of Hogwarts including helping Minerva McGonagall and Kingsley Shacklebolt fight with Voldemort. And though the Dark Lord was weakened thanks to Harry's heroic sacrifice, Slughorn was known to have also "dispatched" a few of his Death Eaters during the same battle.