How about any three random Gundam pilots? We could just crush anyone we were fighting under our giant robot feet.
Otherwise...
Fictional
Kratos, because he kills Gods for fun
Byakuta Kuchiki, because he kills you with style while making it look easy
Ryu (from Breath of Fire), dragon transformations FTW
Real
Bruce Lee, because he's Bruce Lee, dammit!
The real King Leonidas from Sparta, the real guy was pretty bad-ass if only because he stayed behind with 300 Spartans and an assortment of other soldiers (the last stand consisted of about 1400 soldiers) to fight a seemigly limitless enemy while the remainder of their force retreated
Simo Häyhä, known as the White Death, he was a soldier in the Finnish army that had 505 confirmed sniper kills and a total of 705 confirmed kills, all of which he ammased in less than 100 days