Ronald Reagan (1911-2004)
His main accomplishment was that he played a key role in hastening the demise of the Soviet Union. He had the moral clarity to see the Evil Empire for what it was, and he had the courage to implement that clarity in words and deeds. The Soviet Empire would have eventually collapsed under the weight of its own 'internal contradictions' -- to employ a phrase that Marxists loved to (mis)apply to capitalism. But without the resoluteness of Reagan, Margaret Thatcher, and a couple of outstanding Poles (Karol Wojtyla and Lech Walesa), the Soviet Empire might have schlepped on for another decade or two.