Emperor
The leaders of other countries who said they ruled the whole world or called themselves "King of Kings" are frequently also called emperors in English. For example, the old rulers of China (Huangdi), Iran (Shah), and Ethiopia (Negusa negast) are all known as emperors in English. There have also been emperors of France, Brazil , and Mexico, and the rulers of the United Kingdom called themselves the Emperors and empresses of India for a while.