From Sectumsempra to the fearsome Fiendfyre, here are some of the darkest spells in Harry Potter (that aren't Unforgivable Curses).

Imperio, Crucio, Avada Kedavra: the three unforgivable curses of Harry Potter. But we have some questions that we can't quite find answers to.

The Harry Potter universe introduced readers and viewers three Unforgivable Curses. We explain each curse and which was the worst.

On Buffy the Vampire Slayer, Chosen One Faith went very bad, very quickly. Then she started on the rocky road to redemption.

The Unforgivable Curses are introduced in Harry's fourth year in the Goblet of Fire. It's during feigning Mad-Eye Moody's Defense Against the Dark Arts class that Harry sees first-hand the spell that killed his parents. The Killing Curse emits green light and instantly kills its target. The Cruciatus Curse inflicts pain, and the Imperious Curse works to control its victims.