AMERICAN CROCODILES -- Florida
As an apex predator, nothing can hurt these big guys aside from armed humans, or even bigger crocs -- which is why they defy the food chain by eating everything from fish and snakes to wild boars, dogs and calves (and probably also polar bears, sharks, and cougars). Between their crushing (1,000lbs) weight, their lethal chompers, and powerful tails, an average of five Floridians are attacked annually. In May 2006, however, crocs killed three in the space of one week.
Save yourself: Run like hell, in a zig-zag pattern; this reptile’s tiny legs leave him unable to master quick turns.