12 Most Deadly Spells In The Harry Potter Universe

5. Fiendfyre

And continuing on the fire thread, the most notorious of all fire curses in Harry Potter's world is undoubtedly Fiendfyre, a spell more readily characterised as almost living in comparison to other spells. It is the only spell in all of the films and movies that seems to get out of control of the caster, which makes it one of the most dangerous of all and the least advisable to use.

But there's no doubting the effectiveness of it. Not only is it powerful enough to destroy a Horcrux, but the cursed fire is also capable of more simple, devastating tasks like roasting people alive. And it does so with a theatricality usually reserved for only the most skilled wizards, with no consideration for the caster either. Because it's not like you'd expect Gregory Goyle to be able to wield any magic with such flare.