I don't see this coming up a lot in western history. In China people have been saying "assisting Emperor Jie in his carnage" (助桀为虐) for centuries. Jie was known for his cruelty and extravagance and he was the first emperor to be disposed from a revolt. It originated from Sima Qian's book Records of the Grand Historian where he described Liu Bang (later Emperor Gaozu of Han) wanted to settle down and enjoy the palace life after conquering the state of Qin. His adviser told him that settling down right now would be like assisting Emperor Jie, he would need to defeat warlord Xiang Yu first.

Here's how terrible Emperor was:

According to Bamboo Annals (my rough translation): "He neglected national affairs and welfare of the people, built palaces with rooms made out of jade and stairs out of ivory instead. He executed all advisers who try to persuade him to do good (including one with cannon).

According to Biography of Exemplary Women: "He took an immoral woman as a concubine and allowed her to torture human for entertainment. He built a pond filled with liquor for her then ordered thousands of men and women to drink the pond dry and have large orgy, then simply laughed when they drowned." (Here's an illustration from the book)

According to Lüshi Chunqiu: "He forgoes all morality and violated countless women regardless of age."

Judas, Pontius Pilate, the Pharaoh of Exodus, and King George III was used by Americans after the revolution.

Ghengis Khan appears frequently, as does Attila the Hun. Savonarola comes up because his name is so much fun. Mao arises from dung of course, and Ho he Wins, with no remorse.

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