The villain's own weapon or malicious plan is the cause of his downfall and/or death. This could be something as big as a Mad Scientist who creates monsters and/or a Weapon of Mass Destruction getting killed by his own creation, or as small as prankster accidentally setting off his own trap. In media intended for young children, it is often a Death by Irony that releases the hero from the unpleasantness of actually killing their enemy; a more specific type of Self-Disposing Villain. If the Hero is not responsible for the death in any way, it can also be a Karmic Death.