I've not had any close encounters with anything more dangerous than a water moccasin. And that cotton mouth was actually snapping for my legs, so that would've sucked. Second most dangerous was when I was hiking through a small ravine, and I had crouched down to look at a fossil (I live in Texas. Yes, there are places where you can just pick up fossilized shells and what have you), when I looked up, there was ANOTHER water moccasin level with my eyes about eight inches away from me. I just backed away VEEEEEERY slowly, and didn't have an issue.
Beyond that? Not really. Typical dogs and cats, and the occasional rat snake in suburbia that I had to rescue my neighbors from (and vice versa), but that's pretty much it.