1). He slaughtered millions of Jews. 2). Was responsible for the death of millions from three separate continents. 3). Put many European countries in ruins. 4). Game his country a bad name, and ruined there economy. 5). Was the reason the Japanese tried to conquer the South Pacific causing all the deaths there, and Pearl Harbor.
On that note, he was the most evil man in History. And i wish he had not poisoned himself, so he would have been captured, punished horribly and painfully, then suffered a public execution.