king

noun [专属名词]君主，国王；某物之王，首屈一指者；（国际象棋中的）王；极具影响；（纸牌中的）老K；（英国）男性国王在位时使用的国歌

If you describe a man as the king of something, you mean that he is the most important person doing that thing or he is the best at doing it. ^{首屈一指的男性; 佼佼者}