...none other than President George W. Bush.
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According to Jim Kelly, one of the magazine's writers, the winner must be "the person or persons who most affected the news and our lives, for good or for ill, and embodied what was important about the year, for better or for worse."
I didn't even know this, but in 1938, Adolf Hitler was Person of the Year and Josef Stalin was on the cover twice in 1939 and 1942.