Cui Yan
Once, when Cao Cao was about to meet an emissary from the Xiongnu, he felt that he looked ugly and might not be able to command respect so he ordered Cui Yan to impersonate him while he carried a sword and stood beside Cui, pretending to be a bodyguard. After the meeting, Cao Cao sent someone to ask the Xiongnu emissary, "What are your thoughts about the King of Wei?" The Xiongnu emissary replied, "The King looks handsome and extraordinary. However, the man who was carrying a sword and standing beside him is a real hero." Cao Cao had the emissary killed when he heard that.