A Destroyer of Innocence is a type of villain who is responsible for a "loss of innocence". A "loss of innocence" occurs when a sympathetic and (usually) somewhat defenseless character is broken or harmed in some way or similar; this often invokes great feelings of anger by audiences and marks a common Moral Event Horizon. It can also refer to an event that causes unprecedented outrage in society, such as child murder and terrorist attacks, which challenges our concepts of what people can do to each other. Often, victims whose innocence are lost would never be the same person they used to be. Their opposites are Protectors of Innocence.

Destroyers of Innocence are villains who effectively "destroy" the innocence of a story, setting or character; they are often especially wicked beings who ruin lives and their crimes can never truly be reversed as it erases the concept of "innocence", though some rarer examples do not fully know they are responsible for this occurring.

Examples of this type of villain are as follows:

1. Characters who abuses/corrupts a child or someone with a childlike mentality (many "Fagin" types fall into this category).
2. Characters whom a protagonist has admired deeply in the past (even without their knowledge); upon finding out the character's true nature, the protagonist is visibly distressed. 
3. Characters who betray loved ones, family, or friends, especially if their betrayal is extremely brutal and treacherous in nature.
4. Characters who mastermind a particularly shocking event, such as a terrorist attack or massacre of innocents, which in turn causes a deep and lasting "loss of innocence" in his or her setting. The event itself can also count if it has profoundly challenged people's perception of the world.
5. Characters who apparently seems to be harmless or even innocent, but it is only one facet to hide its nature and can easily commit atrocities.
6. Characters who turn their victim to the dark side, often developing the "Evil Vs. Evil" scenario where their victim seeks revenge on those who destroyed their innocence.