Willie the Wisp.
I can kill it well enough when I sneak-shoot it - 4-5 shots or so and it's history. But if it sees me,
I am. I hate those buggers. There's mountain lions too, but at least you're outside and with some luck you make it to some place with guards. Argh. I don't get why I encounter Willies either, I am only frigging level 8!

Being good means getting better.