The term 'Butterfly Ruler' is a nickname given to the Chinese EMPEROR Kangxi, who ruled from 1661 to 1722. He was the fourth EMPEROR of the Qing Dynasty and is considered one of the greatest emperors in Chinese history. The crossword solutions for this term are 'EMPEROR' (7 letters) and 'MONARCH' (7 letters). Both words refer to a sovereign ruler, with EMPEROR being a title used by rulers of an empire and MONARCH being a title used by rulers of a kingdom.