10 Deadliest Spells In The Harry Potter Universe

What does it do? Allows the caster to fully control the will of their victim - and can be used to make other people kill themselves.

Imperio is an Unforgivable Curse that's more indirectly deadly than 'in-your-face' deadly. It won't cause explosions, cuts or even instant death, but it will give you full control over another person's actions - rendering them completely helpless.

We see Imperio being used by Barty Crouch Jr (when disguised as Alastor Moody) during Harry Potter and the Goblet of Fire; Barty casts the spell on a spider to demonstrate its effects to his class of fourth-year students, mentioning that he can make the spider do anything - even "drown herself". Feasibly, he could make the spider kill itself in any manner he sees fit, and that makes Imperio one hell of a force to be reckoned with.

We later see Viktor Krum under the influence of the spell, as he attacks Cedric Diggory in the maze with no control over his actions, or state of mind. Imperio certainly isn't outright deadly, but it's a scary proposition, and once you manage to get someone under its effects it can be as potent as you want it to be.