Lets look at the evidence...
Aliens, robots, undead, animals and monsters seem to have little to no chance upon encountering humans. They may be bouyed by initial wins, but the closer they get to their goal of defeating any sized group of people, the surer their defeat looms. From the cold depths of space to the alien home planets, or in Earth jungles or cities, nothing is so dangerous to a hostile plan as an endangered human. Even alone, outnumbered, on foot, wounded and armed with little more than a bladed weapon or a light machine gun, a human opponent is not to be taken lightly.
So the question is which amongst the humans is the most deadly? Its not so clear cut, but the chances of winning seem to be incredibly improved if you are:
* Photogenic and aged under 40.
* A group outsider, misunderstood or shunned.
* You are wrongfully accused of a crime.
* You are ex police and/or special forces OR if you have no military training whatsoever.
* Your superiors are evil and dislike you.
* Speak with American accent.