Bruce Lee [http://en.wikipedia.org/wiki/Bruce_lee] is the obvious answer. Pound for pound, likely one of the strongest men ever.
I'm also partial to Risto Ryti [http://en.wikipedia.org/wiki/Risto_Ryti], the fifth President of Finland. He's not a badass in any traditional sense of the word though. What he did was, he basically cheated aid against the Soviet Union out of Germany. In 1944, Ryti made a "personal" agreement with the German foreign minister, Ribbentrop, to continue fighting the Soviets in exchange for supplies (which Finland was running low on at this point) from Germany.
The Finnish front now bolstered by Germany, the Red Army soon decided that the war just wasn't worth the trouble, and peace talks were ready to begin again. That's when Ryti resigned as President and declared that his agreement with Ribbentrop was completely informal, and with him alone, not Finland.
The plan wasn't his alone, but he's the one who ended up taking the fall for it. Pressured by the Soviet Union, he was tried as responsible for the Continuation war and sentenced to ten years. He never served the full sentence, as he was hospitalized in 1949 and paroled some time after. He died in 1956 at the age of 67, due to his failing health.
It's just so deliciously devious.