That's a tough one, because a lot of times the guys that make the best fighters are fairly unassuming in their presence. Look at the UFC champions: Jose Aldo, Frankie Edgar, GSP, Anderson Silva, Jon Jones, and Cain Velasquez. Out of all of those, which of them would look all that badass if you saw them walking down the street? Cain maybe?
That said, I pick the unassuming, unlikely hero, the Rocketeer!