For sheer brutality and international recklessness, I would probably make the obvious choice of Hitler, with Stalin and Saddam Hussein coming in a close second.
One of the more interesting cases, however, is Said ibn Taimur, Sultan of Oman from 1932 to 1970. Despite Oman's tremendous oil wealth, the sultan made the concious and unprecedented decision NOT to let his country modernize. Sultanates are an ancient form of government, and the sultan feared that the first act of a modernized and well-educated Oman would be to remove him from power.
Thus, the only paved road in the entire country led from his palace to the airport. Eyeglasses were banned, and the gates to the capital city were sealed every night, Aladdin-style.
Thankfully, he was eventually overthrown by his son.