3. The brown recluse spider
While the black widow gets all the glory and glamour in the death-giving tiny spider world, the brown recluse is almost as deadly, and more common, to the U.S. The spiders aren't typically aggressive, but when they bite, it really, really sucks. Their noshes basically kill your skin cells, causing vacuous, gaping holes that can lead to some serious, life-threatening, Civil War-style gangrene.