Alligators aren't notably aggressive, they'll only come after you if they think you're prey or you step on them. A snake will crawl away if it possibly can rather than bite you. Sharks, according to everything I've read about them, will only attack you if you're imitating a seal. You have the most to fear from a dog. They're very hard to stop, more so than most tough guys think, they'll absolutely tear you to shreds if they're not wearing a collar or something you can grab hold of to control them.
Here's my scary Pit Bull. You couldn't get him to bite you if you tried.
