9. Wild Boar
There are now more than 5 million of these wild hogs living in 39 U.S. states — so many that the Federal government is working to cull their numbers. Wild pigs travel in groups of up to 15, weigh several hundred pounds, can be extremely aggressive, and have razor-sharp tusks. It is not uncommon for hunters to be gored, and their dogs to be killed, during hunts.